DEV Community: Ranjith srt

shell scripting

Ranjith srt — Wed, 02 Jul 2025 18:24:26 +0000

Microsoft apps :

i Ubuntu

Enable WSL :

setting - search turn on off features - on windows subsystem for linux - restart

visual studio code - Extension - WSL

pwd
ls
touch main.sh

cat/etc/shells

chmod +x main.sh

run script :

output:

print :

variable :

variable rules :

type of variables :

commend

environment variables or system variables :

export AGE=26 -set env var
printenv - list env

read - input

operator's:

control statements:

if syntax :

if [expression] True or false
then
statement
fi

Example :

if Else syntax :

if [expression] True
then
statement 1
else Fasle
statement 2
fi

Else if :

if [ expressionl ]
then
statementl
statement2
elif [ expression2 ]
then
statement3
statement4
statements
else
statement 5
fi

Example :

/bin/bash

read -p "Enter a number:" number

if [ $number -gt 10 ];
then
echo "The number is greater than 10. "
elif [ $number -eq 10 ] ;
then
echo "The number is equal to 10. "
else
echo "The number is less than IO. "
f1

Nested if :

if[ expressionl ]
then
statementl
statement2
else
if[ expression2 ]
then
statement3
f1
f1

switch case :

loops :

For loop :

function :

f arg :

Harsha - lix

Ranjith srt — Sat, 21 Jun 2025 17:25:26 +0000

touch file1
cp file1 file2
mkdir dir1
cd
pwd
ls

abs - cd dir1/file1

rls - cd home
cd dir1
cd file1

cd .. - 1 step backward

cd ../.. - 2 srep backward

cd - - previous dir/folder

cd - home

cd ~ - home

cp file1 file2 - file
cp -r dir1 dir2 - directory

find -name dir1
find .-name dir1

find -name file1

ln -s file1 soft-link
ln file1 hard-link

find h*
find ?ello
find hello[0-9]

ls -l - option

ls -la - multi option

ls -l hosts - argument's

sudo useradd ak - create user
sudo passwd ak - set passwprd
cat/etc/passwd - verify user create or not
su ak - swith to ak user
passwd - change ak user password
whoami
pwd

vi file1
i - insert
ESCPE
:wq - write and save
:q! - not save
:q - quit
dd - delete line
shift + z - press z 2 times - save and quit

cat > file1
"HI iam updated"

cat>> file1
"HI iam updated by append"

echo "HI iam updated" > file1
echo "HI iam updated by append" >> file1

vi file1
i - insert
ESCPE
:wq - write and save
:q! - not save
:q - quit
dd - delete line
u- replace
x - 1 word dlt
/g - search
:set nu -set numbers
shift + z - press z 2 times - save and quit

cat file1 - display file contents
more sample.txt - 100vh
less sample.txt - 100vh
q -quit

head file1 - 1st 10 lines
head -n 5 file1 - 1 to 5

tail file1 - last 10 lines
tail -n 5 file1 - last 5

whatis ls
ls --help
man ls

chmod u-r sample.txt
chmod u+w sample.txt
chmod u-e sample.txt

chmod 444 - r
chmod 777 - rwe

chgrp root file_updated
chown root file_updated

ls -l | tail ls-l input | tail output ls last lines display
ls -l | head

grep g file1
grep -i g file1
grep 4 file1

grep -n g file1

grep -v g file1

egrep "one|two" file1

ls -l

ls -l | sort

ls -l | sort -r

sort file1

sort file1 | uniq

sort file1 | uniq -c

change ownership :

sudo su
chown root file1

group ownership :
chgrp root file11

tar -cvf sample.txt sample

qzip sample.tar - compress

qzip -d sample.tar.gz - extract

sudo useradd ak
sudo passwd ak123

sudo useradd -u 1000 ak - user id

sudo usermod --login ak ajith - rename user

sudo usermod -s /bin/cshell ajith - change shell

sudo userdel ak - delt user

sudo groupdel ak - delt group

sudo userdel -r ak - delt single commend

sudo visudo - ediror

ak ALL = (ALL: ALL) ALL

sudo cat/etc/passwd - verify user

sudo cat/etc/shadow - verify password

sudo cat/etc/group - verify group

su ak

users

wall
Hiii..Hellooooooo

ctrl+D

write ak

Hiii..Hellooooooo
Hiii..Hellooooooo

ctrl+D

hostname :

cat/etc/hostname

sudo vi/cat/etc/hostname

sudo init 6

restart

password schedule:
sudo chage --maxdays 30 ubuntu

sudo chage -w 3 ubuntu

sudo chage -d -1 ubuntu

sudo chage -lastday 0 ubuntu

dls password expired:
sudo chage --1 list ubuntu

log :

cd/var/log

monitor commend :

who
w
id
id ak

networking :

ip link show
ip i

ip address show
ip a

ip route show
ip r

cat/etc/resolv.conf

Is /etc/sysconfig/network-scripts/

cat /etc/sysconfig/network-scripts/ifcfg-eth0

sudo ip route add 192.11.12.31 via

SSH - Putty SCP-winSCP

Ranjith srt — Thu, 19 Jun 2025 16:50:13 +0000

Ubuntu CLI Comments :


sudo apt install openssh-server

After installation, start and enable SSH:

Start SSH service
sudo systemctl start ssh

Enable SSH to run on boot
sudo systemctl enable ssh

Check SSH status
sudo systemctl status ssh

To get your IP address to connect via SSH:
ip a


y - yes

sudo systemctl status ssh - current status
sudo systemctl enable ssh

hostname - ranjith
hostname -i - ip address
ifconfig
ip a

window CLI Commend :
ssh ranjith@192.168.0.102
y - yes

Ubuntu machine password

SSH :

CLI :

sudo apt—get update
sudo apt—get install openssh—server

Tools :

Install - Putty - SSH
I - winSCP - SCP

2.32

SCP - copy files 1 machine to another machine

commend line :

Tool :

Install - winSCP - SCP

Drag and drop - 1 machine to another machine

https://youtu.be/RsTeDuC6xHY?si=g62sUkS7iN3_LJBw

mobaxterm

Ubuntu - VM

Ranjith srt — Thu, 19 Jun 2025 15:43:51 +0000

https://youtu.be/oIOYMGra9oA?si=_qhj4IRhxl9768pY

SRTechOps Linux

Ranjith srt — Wed, 18 Jun 2025 16:32:28 +0000

Basic commends:

SSH Server :
🔧 1. Install SSH ServerRun this on Ubuntu (not Windows):

sudo apt update
sudo apt install openssh-server

🔄 2. Start the SSH service

sudo systemctl start ssh

3. Enable SSH to start on boot

sudo systemctl enable ssh

4. Check SSH status

sudo systemctl status ssh
Make sure it says: active (running)

Extra: Check if Port 22 is Open

sudo ufw allow ssh
sudo ufw enable

Then verify:

 sudo ufw status

ssh ranjith@192.168.0.102

🔐 whoami

→ Shows the current logged-in username
📝 Example: whoami → srtechops

📂 pwd

→ Prints the current working directory path
📝 Example: /home/srtechops

📁 mkdir – Make Directory

→ Creates folders (one or more)
📝 Example: mkdir sample → Creates a folder named "sample"

mkdir devops aws azure → Creates multiple folders

rmdir – Remove Empty Directory

→ Deletes empty folders only
📝 Example: rmdir sample

rmdir devops aws azure

📋 ls – List Files and Directories

→ Shows items inside the current directory
📝 Example: ls

ls -l → Long format

ls -a → Shows hidden files

ls -lt → Sort by modified time

ls -ltr → Time-based + reverse

ls -F → Shows file type

ls aws/ → Lists items in aws folder

📄 File Commands

📄 touch

→ Creates a blank file

📝 touch file.txt

🗑️ rm – Remove Files/Folders

→ Deletes files/folders

📝 Examples:
rm file.txt → Deletes file
rm -r aws/ → Removes folder + content
rm -rf aws/ → Force delete
rm *.txt → Deletes all .txt files
rm f* → Deletes files starting with f

📖 cat – Read & Write Files

→ Read/write files (no editing lines)

📝 Examples:
cat file.txt → Show content
cat > file.txt → Overwrite content (Ctrl + D to save)
cat >> file.txt → Append content
cat -n file.txt → Show lines numbered
tac file.txt → Show file in reverse

✍️ CLI Text Editors

📝 nano – Easy text editor

nano sample.txt
Save: Ctrl + O
Exit: Ctrl + X

🧠 vi or vim – Advanced text editor

Open: vi file.txt
Type i → Insert mode
Esc → Exit insert mode
:wq! → Save and quit
:q! → Quit without saving
📣 echo – Print in Terminal📝 echo "welcome to devops class"

➕ To save output:

echo "welcome" >> sample.txt → Auto creates file
📜 History & Search📜 history – Shows command history📝 Examples:

history

history -d 55 → Delete entry 55
history -c → Clear history
history >> file.txt → Save to file

🔎 grep – Search in text

📝 Examples:
grep "git" file.txt
grep -i "g" → Case-insensitive
grep -i -c "g" → Count matches
grep -i -n "g" → Show line numbers
grep -i -v "g" → Show lines without match

🔁 Combine with history:

history | grep -i "ls"
history | grep -c "ls"

🛠️ sed – Stream editor

📝 Examples:
Replace for display only: sed "s/c/c++/" file.txt
Replace & save: sed -i "s/py/python/" file.txt
Case-insensitive: sed -i "s/py/python/I"
Delete last line: sed -i '$d' file.txt
Delete line 2: sed -i '2d' file.txt
Delete lines from 6 to end: sed -i '6,$d' file.txt

🛠 File/Folder Movement & Copy

🚚 mv – Move or Rename

📝 Examples:
mv js java → Rename
mv file folder/ → Move
mv .hidden visible → Unhide
mv file folder/newname → Move + rename

📋 cp – Copy files/folders

📝 Examples:
cp a.txt b.txt → Copy file
cp a.txt folder/ → Copy into folder
cp -r folder1/ folder2/ → Copy folder

🔼 File View Commands

🔼 head – First few lines
head file.txt → First 10 lines
head -n 5 file.txt
🔽 tail – Last few lines
tail file.txt → Last 10 lines
tail -n 2 file.txt
tail -f file.txt → Live log view

🗃️ Compression

🗜️ zip – Compress files

📝 Examples:
zip name.zip *.txt
zip -sf name.zip → Show content
zip -d name.zip file → Remove file
zip -e secure.zip *.txt → Password zip
unzip name.zip → Extract

📂 tar – Archive tool

📝 Examples:
tar -cf file.tar *.txt → No compression
tar -czvf file.tar.gz *.txt → With compression
tar -tvf file.tar → Show detailed content
tar -xvf file.tar → Extract

🌐 Network Tools

🌐 wget – Download file📝 Example: wget https://example.com/file.zip

🔐 ssh – Remote login

📝 Example:

ssh user@ip
ssh srtechops@gmail.com

🔑 Password protected login

🔐 GPG – Encrypt/Decrypt🔒 Encrypt: gpg -c file.tar🔓 Decrypt: gpg -d file.tar.gpg > file.tar

👤 USER MANAGEMENT

$ - Normal user - access file and directories

- Admin root User or Root user - access to All

(install, uninstall apps and update)

su root
password: root123
su - root

adduser :

useradd ranjith

automatically create user account group and home

set password:
passwd ranjith123

cat /etc/passwd - show all users

cat /etc/group - show all groups

su - ranjith - swith home directory

user rename :

usermod -l ranjith ranjithkumar - l new log

group rename :

groupmod -n ranjithkumar ranjith

renane home dir :
mv ranjith ranjithkumar

Delete user :

userdel ranjithkumar

group automatically deleted

Delete home dir :

rm -rf ranjithkumar

userdel ranjithkumar -- remove

👤 USER MANAGEMENT

💡 User Types

$ → Normal user (limited access)

# → Root user (full access: install, delete, update)

🔐 Switch to Root

su root
# OR
su - root

➕ Create User

useradd ranjith      # Add user only (no home)

adduser ranjith      # Recommended – creates home + group + prompts password

🔑 Set Password

passwd ranjith

📜 View All Users and Groups

cat /etc/passwd     # List all users

cat /etc/group      # List all groups

🔄 Switch User

su - ranjith         # Switch to user and home

✏️ RENAME USER / GROUP / HOME
🧑 Rename User

usermod -l newname oldname

# Example:

usermod -l ranjith ranjithkumar

👥 Rename Group

groupmod -n newgroup oldgroup

🏠 Rename Home Directory

mv /home/oldname /home/newname

usermod -d /home/newname -m newname

🗑️ DELETE USER / HOME / GROUP
❌ Delete User Only

userdel ranjith

❌ Delete Home Directory

rm -rf /home/ranjith

🔥 Delete User with Home Directory

userdel --remove ranjith

💡 Group is NOT deleted automatically unless it's a private user group and unused.

🔐 File Permissions

Permission types:

r = read (4)
w = write (2)
x = execute (1)

🛠️ Change with chmod:

Examples:

chmod u+x file → Add execute

chmod g-r file → Remove read

chmod o-rwx file → Remove all from others

chmod 777 file → Full access

chmod 600 file → Owner only

👥 Change Ownership:

Owner: chown harini file.txt
Group: chown :dev file.txt
Both: chown harini:dev file.txt
Directory: chown -R user:group folder/

🔍 File Info & Search
🔍 Find OS: cat /etc/os-release
🔍 Find binary: whereis git
🔍 Search: find -name f1.txt
🔍 Find empty files: find -type f -empty
🗑️ Delete empty dirs: find -type d -empty -delete

🔗 File Linking

🔗 Hard Link: ln file.txt hard.txt
🔗 Soft Link: ln -s file.txt soft.txt

 Kill:

📊 Process Management
📊 Top Processes: top
Normal: kill 2693
Force: kill -9 2693

🌟 What is crontab?

crontab stands for "cron table". It's a file where you define tasks to run automatically at a set time or date.

🔁 Cron = scheduler📄 Crontab = list of scheduled tasks

🔧 Basic Crontab Command

 crontab -e Edit your crontab file
crontab -l  List current cron jobs
crontab -r  Remove all cron jobs
crontab -u username -l  View cron for another user (root only)

Crontab Syntax


*  *  *  *  *  command_to_run
|  |  |  |  |
|  |  |  |  └──── Day of the week (0 - 6) [Sun=0]
|  |  |  └─────── Month (1 - 12)
|  |  └────────── Day of the month (1 - 31)
|  └───────────── Hour (0 - 23)
└──────────────── Minute (0 - 59)

📅 Common Examples

Time    Crontab Syntax  Description
Every minute    * * * * *   Runs every minute
Every hour  0 * * * *   Runs at minute 0 of every hour
Daily at 5am    0 5 * * *   Runs at 5:00 AM every day
Every Monday at 3pm 0 15 * * 1  Runs at 3:00 PM on Mondays
On Jan 1st at midnight  0 0 1 1 *   New Year execution

📂 Run a Script with Crontab
Suppose you have a script at /home/user/backup.sh Make it executable:

chmod +x /home/user/backup.sh
Now schedule it (e.g., every day at 2 AM):

0 2 * * * /home/user/backup.sh

✅ Tips

Always give full paths (e.g., /usr/bin/python3, /home/user/script.sh)
Use >> /path/to/logfile.log 2>&1 to log output and errors
Edit crontab using crontab -e
🧪 Test Crontab
Try a quick job:

* * * * * echo "Hello from cron!" >> /home/user/cronlog.txt

This appends "Hello from cron!" to the file every minute.

✅ 1. Shutdown Immediately

sudo poweroff
sudo shutdown now

✅ 2. Shutdown After 1 Minute

sudo shutdown
(Default is 1-minute delay)

✅ 3. Shutdown at a Specific Time

sudo shutdown 22:00
(This shuts down at 10:00 PM)

✅ 4. Restart Instead of Shutdown

sudo reboot

✅ Cancel Scheduled Shutdown

sudo shutdown -c

SRTechOps Note's

Ranjith srt — Wed, 18 Jun 2025 05:13:04 +0000

os haven't not communicate apps and hardware's.

os use running applications and perform some tasks.

application developed by program.

humans can't communicate with directly hardware's. EX (speakers)
hardware's understand to 0 and 1s
os is a program. (c,c++,python, shell ...)
humans communicate to hardwares with help of os.

Different type os :

windows os, Linux,mac,unix

windows :

GUI - BUILD in program - user friendly - paid os - virus attacks possible - not open source - not secure
CLI - Bulid in program

Linux:

512 gb - 4 cpu - 120gb

Linus is free and open source.
secure
Linux famous for CLI. and little bit basic GUI
created by linus Torvalds ;
unix paid.
unix have some drop backs that resolved made Linux

Linux has been lot of distributions.

Linux foundation - non profits organization

file system:

Basic commends

date - Today date
cal - month calendar

whoami - login user srtechops
pwd - print working directory - /home/srtechops

mkdir sample - make directory (folder)
mkdir sample/ - represent / directory
rmdir sample - remove directory

ls - list files and directories ( present directory)

mkdir - devops aws azure gcp ai - create multiple directory
rmdir - devops aws azure gcp ai - remove multiple directory

touch file.txt - create empty file
rm file.txt - remove empty file

cat :

cat commend used to read and write file can't update lines.

cat file.txt - show file content

cat - write file

cat > file.txt
html
css
js
git

ctrl+d save and exit

cat > file.txt over ride exacting content dlt old line add new lines (override)
python
Django

cat >> file.txt append lines
python
Django

cat -n sample.txt - number of lines (1 2 3)
tac sample.txt - revere order

CLI Text Editor

nano text editor

vi
vim

nano sample.txt

ctrl + o - save and write out
ctrl + exit -exit

vi text editor

vi sample.txt

i - insert mood

Escape

:wq! - save and quit
q - quit
q! - quit not save

echo :
print terminal

echo"welcome to devops class"

echo 'welcome to devops class'

echo"welcome to devops class" >> sample.txt - save content sample.txt

history:

history - show all commend history
history -d 55 - particular commend select and dlt
history -c - clear all history

history >> commends.txt - if not file ..this situation automatically create file.

nano sample.txt - if not file ..this situation automatically create file.

echo"welcome to devops class" >> sample.txt - if not file ..this situation automatically create file.

ls :

ls - list files and directories
ls -l - list detail information
ls -a - list hidden files
ls -l -r -reverse order
ls -l -t - list time based
ls -ltr - order reverse time
ls -F -file types - aws.txt sample/
ls Aws/ - list awa dir files

mv :

mv - multiple purposes rename,move,unhide files

mv js java - rename

mv srtech .srt1 - hide dir
mv .srt1 srtech - unhide dir

mv sample,txt .s1.txt - hide file
mv .s1.txt sample.txt - unhide filles

mv sample.txt aws/s1 -move files

mv sample.txt aws/ - move file ..if file name not mention same name create file automatically

mv aws/document - move dir

cd aws - change dir
cd .. - backward
cd . - current dir
cd - - previous dir
cd ~ - home dir
cd ../../ - backward 2 dir
cd aws/ai/azure/gcp - absolute path

rmdir

rmdir aws/ - dlt empty dir

rm -r aws/ - recoersovely remove files

rm -rf aws/ - force perement delete

rm *.txt - select all ,txt files and remove

rm * - remove all files (global)

rm f* - remove starting letter f files. f1. txt, f3.txt

copy

cp sample.txt s1 - copy contents

cp sample.txt documents/ - copy file and create same name (documents/sample.txt)

cp sample.txt documents/s1.txt - cp destinations s1.txt

cp -r documents/ aws - copy directory

head

head sample.txt - top 10 lines

head -n 5 sample.txt - top 5 lines

tail

tail -f audit.log - monitoring live logs

tail sample.txt - last 10 lines

tail -n 2 sample.txt - last 2 lines

grep - search text

grep "git" sample.txt

grep -i "g" sample.txt - ignore k senstive (upper or lower)

grep -i -c "g" sample.txt - count

grep -i -n "g" sample.txt - numbers

grep -i -v "g" sample.txt - list not matching content

history | grep -i "ls" - list ls

history | grep -i -c "ls" - list ls count

Sed

With out opening nano vi text editor you can delete update or what you are want.

sed "s/c/c++" - c replace c++ not affect original file. Just display temporary.

sed -i "s/py/python programming"sample.txt

Affect original file

sed -i "s/py/python programming/I"sample.txt -
Affect Case sensitive

sed -i '$d' sample.txt _ dlt last one line

sed -i '2d' sample.txt _ dlt specific one line

sed -i '6,$d' sample.txt _ dlt set of lines 6 to last one line

Zip compress and archive

File size Compress panna, archive oru single folder Ullara files pottu veikka

zip devopstools.zip *. txt - compress file

zip -sf devopstools.zip - show files without unzip files.

Note you not unzip file.. Add or delete files in possible.

zip devopstools.zip sample - adding new file to already existing zip file

zip -d devopstools.zip sample

Dlt particular file in zip

Unzip devopstools.zip - extracting files

Set password

zip -e file.zip *.txt

tar archive

tar -cf myfiles.tar *.txt - create archive

tar -cvf myfiles.tar *.txt - bg archive apoo enna nadakuthunu paakalam.

tar -tf myfiles.tar - view files without extract

tar -tvf myfiles.tar - view files full details without extract

extract

tar -xf myfiles.tar - extract file

tar -xvf myfiles.tar - full details

dowload links:

wget

ssh protocol :

ipconfig - machine ip address
ssh srtchops@gmail.com
password: srt123

tar —czvf compressedfile.tar.gz *.txt

gpg —c myfiles .tar - ser pssword

gpg —d myfiles.tar.gpg > myfiles.tar -dlt passw

user management :

$ - normal user

-root user

su root
password: ____

user :

adduser ak - create user
passwd - set password ak

cat/etc/passwd- verify user account create or not

su ak - switch to ak user

group :

cat/etc/group- verify user account create or not

home dir :

cd ~ - /home/ak

deluser ak - dlt user group / user dlt agum..home dir dlt agathu

delt home dir
rm —r ak
rm —rf ak

userdel sangavi --remove - delt all home/userac/group

user name modification :

usermod -l ak ajith - ak to ajith rename

dir name change :

mv ak/ ajith/

grop rename:

groupmod -n ak ajith

password:
sudo su
passwd ak

top

kill 2693

kill -9 2693 force kill

logout

Group management:

create group - groupadd DevTeam

verify group - cat/etc/group

gpasswd -a ranjith DevTeam - add user to group

usermod -aG DevTeam ranjith - add user to group another way

gpasswd -d ranjith DevTeam - dlt user

groupdel DevTeam - dlt group

cat /etc/group - check group

lid -g DevTeam - list group numbers

search files - ls /etc/ | grep "g*”

log files :

cat /var/log/audit/audit.log

tail —n 1 /var/log/audit/audit.log

how to see group numbers :

lid -g DevTeam list group id

gpasswd —a ak devTeam - add group
gpasswd —a vk devTeam

usermod —aG devTeam prem - add group

gpasswd —d ak devTeam - dlt group
gpasswd —d vk devTeam

groupdel devTeam - dlt group

file permission:

change permission

chmod u+x welcome.txt user

chmod u+r welcome.txt

chmod u+w welcome.txt

chmod u+rwx welcome.txt add all permissions

remove permission:

chmod u-x welcome.txt user

chmod u-r welcome.txt

chmod u-w welcome.txt

chmod u-rwx welcome.txt remove all permissions

chmod g+x welcome.txt group

chmod g+r welcome.txt

chmod g+w welcome.txt

chmod g+rwx welcome.txt

remove permission:

chmod g-x welcome.txt group

chmod g-r welcome.txt

chmod g-w welcome.txt

chmod g-rwx welcome.txt

chmod o+x welcome.txt others

chmod o+r welcome.txt

chmod o+w welcome.txt

chmod o-rwx welcome.txt

remove permission:

chmod o-x welcome.txt others

chmod o-r welcome.txt

chmod o-w welcome.txt

chmod +x welcome.txt - Add all users permission execute

-rx-x-x

chmod -x welcome.txt - Add all users permission execute

number permission:

chmod 000 welcome.txt - no access rwe

chmod 777 welcome.txt - all access rwe

chmod 444 welcome.txt - rrr

chmod 111 welcome.txt - xxx

chmod 222 welcome.txt -www

chmod 41 welcome.txt - rx

chown harini hello.txt - change group owner

devTeam members access allowed hello.txt

user owner ownership change at time :

change dir ownership:

packeage manager

redhat os - yum ( yellow dog updater & modified)

ubuntu os - apt ( advanced package tool )

yum install git
yum remove git

rpm -qa show sys install apps

rpm -qa git - git install or not

rpm -q git - search git o or not

yum update

lat version net laa irunthu dowload pannum

sudo yum update os softwares repo ellam update agum

yum upgrade

andha download panna ella filesyum install pannum.

sudo yum upgrade ella software update agum

rpm - redhat package manager

which firebox - firebox file location

rpm -qa show sys install apps

rpm -q - particular app i or not

rpm -q -f /user/bin/firebox - firebox executable file path

rpm -q -l firebox - firebox i location all list files

ls /user/bin/firebox

ls -l /user/bin/firebox

rpm -e firebox - uninstall

rpm install firebox - install

yum install firebox - install

yum remove firebox - uninstall

dnf install git - yum advance future

file sudoers : user permissions

sudoers behave like root ..neccssary to user in sudo group

tail -f audit. log - see live log

tail -n 1 audit. log - live last log

how to give root power sudo power to normal user?

useradd anu

su - anu

visudo file :

cat /etc/sudoers

visudo - edit file

anu ALL=(ALL) ALL - all access

anu ALL=(ALL) /usr/bin/yum - update.dlt apps

anu ALL=(ALL) /usr/bin/yum install git - particular access

anu ALL=(ALL) /usr/bin/yum install * - i all apps

wheel:

cat /etc/group

wheel ALL=(ALL) ALL /usr/bin/yum

lid -g wheel - show wheel group

gpasswd -a anu wheel

sudo lid -g wheel - display wheel group members

os details:

cat/etc/os-release - os info

whereis git - git location

find -name f1.txt - location

find -type f - empty - list empty files

find / -name srtech -

find —type d —empty —delete

soft links and hard links :

shortcut's

ln sample.txt hardlink.txt

original file laa dlt ,edit vela nadantha shortcut filelyum affect agum.

hardlink laa orginal file dlt pannalayum shortcut file orginal file aa ran aagum.

ln -s sample.txt softlink.txt

original file laa dlt ,edit vela nadantha shortcut filelyum affect agum.

orignal file dlt panna softlink work agathu

process management:

ps - process status

ps -ef -

top

kill 786

kill -9 2569

✅ 1. Shutdown Immediately

sudo poweroff

sudo shutdown now

✅ 2. Shutdown After 1 Minute

sudo shutdown

(Default is 1-minute delay)
✅ 3. Shutdown at a Specific Time

sudo shutdown 22:00

(This shuts down at 10:00 PM)
✅ 4. Restart Instead of Shutdown

sudo reboot

✅ Cancel Scheduled Shutdown

sudo shutdown -c

https://youtu.be/kozgg-jUmZI?si=NN0ZPuNMaZHdsl7H

https://youtu.be/ugyNu96k5_Q?si=WPb2glcsFTZqWsGR

https://youtu.be/MQmA1TmR35c?si=yjCpQkm-j9bvSmbu

https://youtu.be/knYTByoBjPE?si=h2Yy3tAgHlpCxMlq

Linux intro

Ranjith srt — Sun, 15 Jun 2025 15:42:37 +0000

Enable windows:

windows - start - features - turn windows fratures on or off

on - virtual machine platform
on - windows subsystem for linux

Restart

window's CLI commends :

wsl --install - i Ubuntu

usname - Ubuntu
passw - ubuntu Default

pwd - /home/ubuntu - home path/username

path - username rendum serinthu dhan home.

uname -a os version

whoami - username

clear CLI :

clear
ctrl+L

history - commends history

mkdir Dummy - create folder
mkdir -p dir1/dir2/dir3 - sup folders

vi Editor :

vi sample.txt

i -insert mood
Escape
:wq - save/quit
:q - quit
:q! - not save
dd - delete
ctrl+ shift + c -copy
ctrl+ shift + v - paste
press d two times helloworld - delete line

sudo apt-get install vim - updrade vim

vim Editor:

vim sample.txt

i - insert
enter - next line
Escape
:wq - save/quit
:q - quit
:q! - not save
: set number - 1 a 2 b 3c
/git - search word

nano Editor :

ctrl + x - save
y - yes
ctrl + x Exit

touch sample.txt - create file

rm sample.txt - remove file
rm txt - remove .txt files
rm - delete all files

ls txt - list .txt files
ls he - list start file name like he

cat sample.txt view content
cat sample.txt >> s1 copy file - append
cat/home/ubuntu/data.log - absl path

cp sample.txt s1.txt old file / copy file

mv sample.txt s1 rename file/ rename
mv .sl hidden file
mv .s1 s1 remove hidden

echo "Hello world " print cli

echo "Hello world " >>sample.txt create file or append mention file

history >> history.txt create file cp commends

ls - list files,file,dir
ls -l long list
ls -a - hidden files and dir
ls -s -sort
ls -r - reverse order
ls -t - time
ls *py - list emd match files
ls file - list start match file
ls

ls -lstr

ls .py - select .py file
ls time - start file

cd - current dir home
cd . - current dir
cd .. last dir
cd ~ home dir
cd - previous dir
cd ../.. - 2 dir back vara

vi .bashrc
source .bashrc - file execute

.bashrc - set Environment variables or program home

set program files home next execute .bashrc file

important:

hard link and soft link

hard link :
ln original.txt hard.txt

soft link :

ln -s original.txt soft.txt

alias p="pwd" short cut

schedule tasks:

2 clicks code run

monitoring live logs:

three type monitoring

top - task manager
ps
ps -aux - runining files

ps -aux | grep data_preocessing.py - particular file

ctrl + z -exit

cat data_process.log - viwe list log

tail -f data_process show live log
tail -10 data_process show live log last 10 lines

kill -9 168858 - force kill

particular file log

download links files images :
wget "http://img" - download

Disk:

df -h Disk free space
du -sh scripts file Disk usage

free -m free memory

free -g ram usages

remove cache :

sudo sh —c "sync; echo 3 >/proc/sys/vm/drop_caches"

zip and tar :

zip f1.zip scripts zip new folder name/zip folder

zip -r f1.zip scripts

ls -lstr | tail -f

unzip f1.zip

tar:

tar -czvf sample.tar scripts/

compress
z - tar type files force
details
verbose - list files
following list

untar :

tar -zxvf sample.tar scripts/

x -extract
z - tar type files force
details
verbose - list files
following list

word count :

wc -w sample.txt - words

wc -l sample.txt - lines

wc -c sample.txt - characters count

order :
sort file1
sort -r file1

sort numbers :

sort -n file1

head :

head sample.txt 1st 10 lines

head -n 5 sample.txt

tail :

tail sample.txt last 10 lines

tail -n 5 sample.txt

grep : search

grep ERROR log1.txt list matching lines
grep -i error log1.txt list -i upper or lower matching lines
grep -v error log1.txt ignore error and list other ines

grep WARRING *.txt global search

grep WARRING *.txt | tail -f

Network commends :

SSH - same network laa connect aa irukka ..en lap friend laptop connect pannalam

SCP - company server oda connrct panna .. ip add ,passw set pani work pannanum server laa

ifconfig - ip address

ssh :

ssh anoter way

2.30
tools:

putty ssh
winscp scp

find :

find . -name log.txt
find . -name ".txt"
find . —type f —size +10M 10mb mela
find . —mtime -1 1 day modification files
find . -empty
find . -name ".tmp" -delete

awk

group management

chomd 777 dummy -files

chomd -R 777 dummy -directory's

scheduling :

crontab -e

crontab formula:

crontab stands for "cron table". It's a file where you define tasks to run automatically at a set time or date.

🔁 Cron = scheduler
📄 Crontab = list of scheduled tasks

🔧 Basic Crontab Command

Command Description
crontab -e Edit your crontab file
crontab -l List current cron jobs
crontab -r Remove all cron jobs
crontab -u username -l View cron for another user (root only)

Crontab Syntax

* * * * command_to_run | | | | | | | | | └──── Day of the week (0 - 6) [Sun=0] | | | └─────── Month (1 - 12) | | └────────── Day of the month (1 - 31) | └───────────── Hour (0 - 23) └──────────────── Minute (0 - 59)

📅 Common Examples

Time Crontab Syntax Description
Every minute * * * * * Runs every minute
Every hour 0 * * * * Runs at minute 0 of every hour
Daily at 5am 0 5 * * * Runs at 5:00 AM every day
Every Monday at 3pm 0 15 * * 1 Runs at 3:00 PM on Mondays
On Jan 1st at midnight 0 0 1 1 * New Year execution

* * * * echo "Hello from cron!" >> /home/user/cronlog.txt

corntab guru website

OFF

Bootstrap

Ranjith srt — Sat, 14 Jun 2025 08:15:26 +0000

Bootstrap 5.3 (Latest)

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Bootstrap Example</title>
  <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/css/bootstrap.min.css" rel="stylesheet">
</head>
<body>

  <div class="container mt-5">
    <h1 class="text-primary">Hello, Bootstrap!</h1>
    <button class="btn btn-success">Click Me</button>
  </div>

  <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/js/bootstrap.bundle.min.js"></script>
</body>
</html>

Container :

Container - 80% width
Container-fluid - 100% full width 

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/h0bloebkvlsirack5f16.jpg)

Container Break points :

Container-sm
Container -md
Container -lg
Container -xl
Container -xxl

Grid :

1 row naa - 12 cols

Col - Ennumber of cols nowrap

col-1 to col-12 12 cols layout automatically wrap

Media Grid system :

Sm - col-sm-* 1 t0 12
Md - col-md-* " " 
Lg - col-lg-* "" 
xl - col-xl-* "" 
xxl - col-xxl-* ""

Offset:

Break points

Offset-1 to 11

Essential Linux Commands for Beginners

Ranjith srt — Tue, 20 May 2025 13:47:21 +0000

🖥️ Basic Output & Info Commands
echo
bash
Copy code
echo "Hello world"
📝 Prints text to the screen.

pwd
bash
Copy code
pwd
📝 Prints the current working directory (folder you are in).

date
bash
Copy code
date
📝 Shows current system date and time.

history
bash
Copy code
history
📝 Shows list of previously used commands.

clear
bash
Copy code
clear
📝 Clears the terminal screen.

📁 Navigation Commands
cd
bash
Copy code
cd foldername
📝 Changes into a folder.

cd ..
bash
Copy code
cd ..
📝 Goes one level back (up) from the current directory.

cd -
bash
Copy code
cd -
📝 Goes to the previous directory.

cd ~
bash
Copy code
cd ~
📝 Goes to the home directory.

📂 Listing Files
ls
bash
Copy code
ls
📝 Lists files in current folder.

ls -a
bash
Copy code
ls -a
📝 Lists all files including hidden ones (starting with .).

ls -l
bash
Copy code
ls -l
📝 Shows more details (like size, permissions) about files.

ls -la
bash
Copy code
ls -la
📝 Lists all files (even hidden) with details.

ls -R
bash
Copy code
ls -R
📝 Lists all files and folders recursively.

ls -r
bash
Copy code
ls -r
📝 Lists files in reverse order.

ls -t
bash
Copy code
ls -t
📝 Sorts files by last modified time.

📝 File Handling
touch
bash
Copy code
touch myfile.txt
📝 Creates an empty file or updates file's modified time.

file
bash
Copy code
file myfile.txt
📝 Tells you the type of file (text, image, etc).

cat
bash
Copy code
cat myfile.txt
📝 Shows the content of a file in terminal.

📖 View Long Files
less
bash
Copy code
less lorem.txt
📝 Opens file in viewer, lets you scroll.

Controls:

q = quit

PgUp / PgDn = scroll

g = go to top

G = go to bottom

/word = search

h = help

📁 Create Folders
mkdir
bash
Copy code
mkdir newfolder
📝 Creates a new folder.

mkdir -p
bash
Copy code
mkdir -p test/test1
📝 Creates nested folders (folders inside folders).

📄 Copy Files
cp
bash
Copy code
cp old.txt new.txt
📝 Copies one file to another.

Copy file to folder:
bash
Copy code
cp text.txt newfolder/
Copy all .txt files:
bash
Copy code
cp *.txt newfolder/
Copy folder:
bash
Copy code
cp -r folder1/ folder2/
Ask before overwrite:
bash
Copy code
cp -i file1.txt file2.txt
✂️ Move / Rename Files
mv
bash
Copy code
mv file1.txt file2.txt
📝 Renames file or moves to a new folder.

Move multiple .txt files:
bash
Copy code
mv *.txt newfolder/
Ask before overwrite:
bash
Copy code
mv -i old.txt new.txt
❌ Delete Files/Folders
rm
bash
Copy code
rm file.txt
📝 Deletes a file.

Delete folder and its content:
bash
Copy code
rm -r myfolder/
Ask before delete:
bash
Copy code
rm -i file.txt
🔍 Search / Help
find
bash
Copy code
find . -name "*.txt"
📝 Search for files (here, all .txt files).

help
bash
Copy code
help echo
📝 Shows help for a command.

man (manual)
bash
Copy code
man ls
📝 Full manual page for a command (press q to quit).

whatis
bash
Copy code
whatis cat
📝 Gives a short description of a command.

🔧 Aliases
Create alias (shortcut):
bash
Copy code
alias mylist="ls -la"
Remove alias:
bash
Copy code
unalias mylist
🔚 Exit Terminal
Exit the terminal:
bash
Copy code
exit

echo - "Hello world"
/ - root
pwd - present working directory

cd - - change directory

cd .. - exit current directory

cd - - previous directory

cd ~ - home directory

ls- list

ls -a - hidden file

ls -l more files details

ls -l -a more datails with hiddenn files details
ls -R

ls -r reversr order sorting

ls -t sort modification time,newest first

touch - create file and touch file (identify modify time)

date - current date

file - text.txt file details

cat - open file and view content

history

clear

less -- less lorem.txt user view content

q - quit

pg up pg down - navigate pages

g move beginning

G - move end

/search

h help

mkdir new folder
mkdir -p test/test1/ folder ulla folder

cp oldfile copy file

cp text.txt newfolder

cp *.txt newfolder select all .txt file

cp -r sub folders

cp -i

mv oldfile newfile (edit and rename)

mv myfile.txt file1.txt

mv f1.txt f3.txt f3.txt newfolder

mv *.txt newfolder ella file newfolder ulla pogum

mv -i

mv -b

rm newfolder

rm -r newfolder folder and folder ulla irukratha ellam repeat ahh dlt pannum

rm -i

find search

help echo

man is

whatis cat

alias shortcut

alias footbar ="ls -la"
unalies remove aliaas

exit

Django

Ranjith srt — Fri, 04 Apr 2025 13:36:38 +0000

🧠 Django Small Notes (Beginner-Friendly)
✅ What is Django?
Django is a Python web framework.

It helps you build websites and web apps quickly.

It comes with built-in features like user login, admin panel, database management, etc.

🔧 Step-by-Step Setup
1. Check Python
bash

python --version
2. Create Virtual Environment
bash

python -m venv venv
3. Activate the Environment (Windows)
bash

venv\Scripts\activate
4. Install Django
bash

pip install Django
5. Check Django Version
bash

django-admin --version
6. Create Django Project
bash

django-admin startproject myapp
7. Go into the project folder
bash

cd myapp
8. Run the development server
bash

python manage.py runserver
9. Apply Migrations (very important!)
bash

python manage.py migrate
🛠 What These Commands Do:
venv\Scripts\activate → Activates virtual environment

startproject → Creates new Django project

runserver → Starts local web server

migrate → Creates tables in your database

createsuperuser → Creates admin login

🌐 Default Django URL
After running the server, open:

cpp

http://127.0.0.1:8000/

Networking & Web Fundamentals

Ranjith srt — Wed, 26 Mar 2025 17:22:10 +0000

Introduction to HTML, Web Pages, and Networking

1️⃣ Client (Frontend) – The part users see and interact with.

2️⃣ Server (Backend) – The part that processes requests, handles logic,

and connects to the database.

https://youtu.be/2WsianlhxDI?si=vVcWuVEylfGdyBQd

1️⃣ What is a Client?

The client is the user-facing part of an application.It sends requests to the server and receives responses from it.In MERN, the client is built using React.js.

📌 Example Clients:

Websites like Instagram, Facebook, and Twitter.Mobile apps that fetch data from an online server.

 📝 Key Notes on Clients

 ✔ Runs in the web browser.✔ Displays UI elements like buttons, forms, and text.✔ Sends requests to the backend to fetch or update data.

2️⃣ What is a Server?

The server processes requests from the client and sends back responses.It performs operations like fetching, storing, or updating data in a database.In MERN, the backend is built using Node.js and Express.js.

📌 Example Servers:

Instagram’s backend, which stores user posts and comments.Google’s search engine backend, which processes search queries.

📝 Key Notes on Servers

✔ Runs on a web server (e.g., localhost or cloud).✔ Handles data processing and business logic.✔ Communicates with the database (MongoDB) to store or retrieve data.

3️⃣ How Do Client and Server Communicate?

1️⃣ The client makes a request (e.g., "Show me all posts").
2️⃣ The server processes the request and fetches data from the database.
3️⃣ The server sends a response back to the client.
4️⃣ The client receives the response and displays the data to the user.

🖼️ Diagram: How Client and Server Work Together

`[ Client (React.js) ] <-------> [ Server (Node.js + Express) ] <-------> [ Database (MongoDB) ]`

`The client requests data from the server.The server fetches data from the database and sends it back.The client then displays the data to the user.`

✨ Summary

Feature Client (Frontend)   Server (Backend)
Technology Used React.js    Node.js, Express.js
Main Role   Displays UI, makes requests Handles logic, processes data
Where It Runs   User’s browser    Web server (e.g., localhost, cloud)
Example Instagram website   Instagram’s backend handling posts

1️⃣ What is LAN? (Local Area Network)

A LAN (Local Area Network) is a network that connects computers and devices within a small area, such as:

A home
An office
A school

📝 Key Points about LAN

✔ Connects multiple devices using Wi-Fi or Ethernet cables.✔ Devices in a LAN can share files, printers, and internet connections.✔ A router or switch is used to manage the connections.

📌 Example of LAN:

In a school, all computers in the computer lab are connected via LAN.In an office, employees share files through a LAN network.

🖼️ Simple LAN Diagram

`[ Computer 1 ] --|[ Computer 2 ] --| --> (Router) --> Internet[ Printer ] --|`

2️⃣ What is HTTP? (HyperText Transfer Protocol)

HTTP (HyperText Transfer Protocol) is a set of rules for how web browsers and servers communicate over the internet.

📝 Key Points about HTTP

✔ It allows users to access websites.✔ It works on port 80 by default.✔ Websites using HTTP are not encrypted (unsafe).

📌 Example of HTTP in Action:

When you type http://www.google.com in a browser, your browser requests the webpage from Google’s server using HTTP.The server then sends back the page, and you see it on your screen.

🖼️ Simple HTTP Communication

[ Client (Browser) ] ---> HTTP Request ---> [ Server ] 

[ Server ] ---> HTTP Response ---> [ Client (Browser) ]

🚀 What is HTTPS?

HTTPS (HyperText Transfer Protocol Secure) is the secure version of HTTP.

✔ It encrypts data using SSL/TLS to protect user information.✔ Websites with HTTPS use port 443 instead of port 80.✔ Example: https://www.google.com (🔒 Secure website).

✨ Quick Comparison:

Feature LAN HTTP
Meaning Local network for connecting devices    Protocol for web communication
Used For    Sharing files, internet, printers in small areas    Accessing websites over the internet
Security    Private (limited to local area) Public (open to internet users)
Example Office network, school Wi-Fi    Web browsing (Google, Facebook)

`1️⃣ What is an IP Address? (Internet Protocol Address)`

`An IP address is a unique number assigned to every device connected to the internet. It helps computers identify and communicate with each other.`

📝 Key Points about IP Address

`✔ It acts like a home address for devices on the internet.✔ Websites, computers, and phones all have IP addresses.✔ Example of an IP address:`

`IPv4: 192.168.1.1IPv6: 2001:0db8:85a3:0000:0000:8a2e:0370:7334`

📌 Example of How IP Works

`When you type www.google.com, your browser translates it to Google’s IP address (e.g., 142.250.190.14) to load the website.`

`🖼️ Simple IP Address Concept`


[ Your Device ] ---> [ 142.250.190.14 (Google Server) ] ---> [ Google Website ]

2️⃣ What is a Domain Name?

A domain name is a human-friendly name that represents an IP address. Since IP addresses are hard to remember, domain names make it easier.

📝 Key Points about Domain Names

✔ A domain name is like a nickname for an IP address.✔ Instead of typing 142.250.190.14, you can type www.google.com.✔ Domain names have extensions like .com, .org, .net.

📌 Example of Domain Names and IPs

Domain Name IP Addresswww.google.com 142.250.190.14www.facebook.com 157.240.221.35

🖼️ Simple Domain Name Concept


[ You ] ---> [ www.google.com ] ---> [ 142.250.190.14 (Google Server) ] ---> [ Google Website ]

3️⃣ What is Web Hosting?

Web hosting is a service that stores and serves website files on the internet.

📝 Key Points about Web Hosting

✔ It is like renting space on a computer (server) to store your website.✔ Web hosting providers include GoDaddy, Bluehost, Hostinger, AWS, and Google Cloud.✔ Types of hosting:Shared Hosting (Cheap, multiple websites share one server).VPS Hosting (Private server space, better performance).Dedicated Hosting (Entire server for one website, expensive)

📌 Example of Web Hosting in Action

`When you visit www.example.com, the browser contacts the hosting server, retrieves website files, and displays the page.🖼️ Simple Web Hosting Concept`


 [ You ] ---> [ www.example.com ] ---> [ Hosting Server (Files, Images, Database) ] ---> [ Website Loads ]

✨ Quick Summary

Feature IP Address  Domain Name Web Hosting
Meaning Unique identifier for devices   Human-friendly name for websites    Stores website files
Example 142.250.190.14  www.google.com  Hostinger, Bluehost
Purpose Identifies devices/websites Makes web addresses easy to remember    Stores websites for online access

Client - Server Architecture

MERN - Html (Day 7)

Ranjith srt — Wed, 26 Mar 2025 17:14:03 +0000

img path | Marquee | entities | symbols | emojis

HTML Semantic Tags

Semantic tags give meaning to the content inside them. They help both search engines and developers understand the structure of a webpage.

1. Structural Semantic Tags

These tags define the layout of a webpage.

📍 <header> - Website Header

✅ Definition: Represents the top section of a page or a section.

✅ Usage: Usually contains logos, navigation menus, and headings.

🔹 Example:


<header>
    <h1>My Website</h1>
    <nav>
        <ul>
            <li><a href="#">Home</a></li>
            <li><a href="#">About</a></li>
            <li><a href="#">Contact</a></li>
        </ul>
    </nav>
</header>

✅ Key Points:

Can be used multiple times in a page (inside <article> or <section>).

- Usually contains branding, logo, and navigation links.

📍 `<nav>` - Navigation Links

✅ Definition: Represents the navigation menu of a webpage.

✅ Usage: Used to group important links like Home, About, Contact.

🔹 Example:


<nav>
    <ul>
        <li><a href="#">Home</a></li>
        <li><a href="#">Services</a></li>
        <li><a href="#">Blog</a></li>
        <li><a href="#">Contact</a></li>
    </ul>
</nav>

✅ Key Points:

Used for menus, sidebars, or footer links.
Should only contain important navigation links.

📍 `<main>` - Main Content Area

✅ Definition: Represents the main content of the webpage.

✅ Usage: Contains the most important information (not repeated in other sections like header or footer).

🔹 Example:


<main>
    <h2>Welcome to My Website</h2>
    <p>This website shares useful programming tutorials.</p>
</main>

✅ Key Points:

Each webpage should have only one <main> tag.
Should not contain <header>, <footer>, <nav>.

📍 `<article>` - Independent Content

✅ Definition: Represents a self-contained, independent piece of content.

✅ Usage: Used for blog posts, news articles, or product descriptions.

🔹 Example:

html
CopyEdit
<article>
    <h2>Learn HTML Semantic Tags</h2>
    <p>HTML has semantic tags that give meaning to content...</p>
</article>

✅ Key Points:

Can contain title, text, images, and links.
Each <article> should make sense even if taken out of the page.

📍 `<section>` - Thematic Section

✅ Definition: Represents a section inside a webpage that groups related content.

✅ Usage: Used for different sections like services, testimonials, or features.

🔹 Example:

 <section>
    <h2>Our Services</h2>
    <p>We offer web development, design, and SEO services.</p>
</section>

✅ Key Points:

Should always have a heading (<h2>, <h3>).
Used for grouping related content.

📍 `<aside>` - Sidebar Content]

✅ Definition: Represents side content like ads, links, or related articles.

✅ Usage: Used for sidebars, advertisements, and related links.

🔹 Example:


<aside>
    <h3>Related Articles</h3>
    <ul>
        <li><a href="#">HTML Basics</a></li>
        <li><a href="#">CSS Flexbox</a></li>
        <li><a href="#">JavaScript DOM</a></li>
    </ul>
</aside>

✅ Key Points:

Not part of the main content.

- Placed beside articles or main sections.

📍 `<footer>` - Bottom Section

✅ Definition: Represents the bottom section of a webpage.

✅ Usage: Used for copyright info, contact details, or social media links.

🔹 Example:


<footer>
    <p>&copy; 2025 My Website. All Rights Reserved.</p>
    <nav>
        <a href="#">Privacy Policy</a> | <a href="#">Terms of Use</a>
    </nav>
</footer>

✅ Key Points:

Used once per page (usually).

- Contains useful links, copyright, and credits.

📝 Summary of Structural Semantic Tags

Tag	Meaning	Use Case
`<header>`	Top section of a page	Logo, navigation, welcome text
`<nav>`	Navigation links section	Menus, sidebar links
`<main>`	Main content of page	Articles, blog posts
`<article>`	Independent content block	Blog posts, news
`<section>`	Thematic section	Grouping related content
`<aside>`	Sidebar content	Ads, related links
`<footer>`	Bottom section	Copyright, contact info

2. Text-Level Semantic Tags

These tags help format and structure text properly to give it meaning. They are useful for SEO, readability, and accessibility.

📍 `<h1>` to `<h6>` - Headings

✅ Definition: Used for headings in a document, where <h1> is the most important and <h6> is the least important.

✅ Usage: Used to structure the document into sections.

🔹 Example:


<h1>Main Heading</h1>
<h2>Subheading</h2>
<h3>Smaller Subheading</h3>

✅ Key Points:

There should be only one <h1> per page.
Helps with SEO (Search Engine Optimization).
Do not use <h1> just for big text; use CSS for styling.

📍 `<p>` - Paragraph

✅ Definition: Used to write a paragraph of text.

✅ Usage: Used for normal content inside a webpage.

🔹 Example:


<p>This is a paragraph. HTML makes it easy to structure content.</p>

✅ Key Points:

Browsers automatically add space before and after <p>.
Do not use multiple <br> tags for spacing.

📍 `<blockquote>` - Quoting a Block of Text

✅ Definition: Used to quote long text from another source.

✅ Usage: Often used for citing references or articles.

🔹 Example:


<blockquote>
    "The only limit to our realization of tomorrow is our doubts of today."
</blockquote>

✅ Key Points:

Browsers indent <blockquote> by default.

- Use `<cite>` inside it to give source information.

📍 `<cite>` - Citing a Source

✅ Definition: Used to cite the title of a book, article, or work.

✅ Usage: Helps indicate the author or reference.

🔹 Example:


<p><cite>The Great Gatsby</cite> is a novel by F. Scott Fitzgerald.</p>

✅ Key Points:

It is usually displayed in italics.

📍 `<q>` - Short Inline Quote

✅ Definition: Used to add short inline quotes.

✅ Usage: Used for quoting words inside a sentence.

🔹 Example:


<p>As Albert Einstein said, <q>Imagination is more important than knowledge.</q></p>

✅ Key Points:

Browsers automatically add quotation marks around <q>.

📍 `<time>` - Representing Date and Time

✅ Definition: Defines a specific time, date, or duration.

✅ Usage: Useful for events, articles, or schedules.

🔹 Example:

 <p>Our meeting is scheduled for <time datetime="2025-03-30T10:00">March 30 at 10 AM</time>.</p>

✅ Key Points:

The datetime attribute makes it machine-readable.

📍 `<address>` - Contact Information

✅ Definition: Used to represent contact details like email or physical address.

✅ Usage: Often used inside <footer>.

🔹 Example:


<address>
    Contact us at: <a href="mailto:info@example.com">info@example.com</a>
</address>

✅ Key Points:

Usually contains emails, phone numbers, or physical addresses.

📍 `<pre>` - Preformatted Text

✅ Definition: Displays text exactly as written in the code, including spaces and line breaks.

✅ Usage: Used for code blocks, ASCII art, or poems.

🔹 Example:

 <pre>
    This text
    is displayed
    exactly as it is
</pre>

✅ Key Points:

Maintains spaces and line breaks.

📍 `<code>` - Inline Code

✅ Definition: Used to display inline programming code.

✅ Usage: Helps show code snippets in a readable format.

🔹 Example:

 <p>To print in Python, use <code>print("Hello, World!")</code>.</p>

✅ Key Points:

Does not apply any syntax highlighting.
Use <pre><code> for longer code blocks.

📍 `<kbd>` - Keyboard Input

✅ Definition: Represents keyboard input (like key presses).

✅ Usage: Used for computer tutorials.

🔹 Example:

 <p>Press <kbd>Ctrl</kbd> + <kbd>C</kbd> to copy text.</p>

✅ Key Points:

Useful for shortcut key instructions.

📍 `<samp>` - Sample Output

✅ Definition: Represents output from a computer program.

✅ Usage: Used for displaying command-line results.

🔹 Example:


<p>The output is: <samp>Operation completed successfully</samp></p>

✅ Key Points:

Often used with <code>.

📍 `<var>` - Variable in Programming

✅ Definition: Used to define a variable in programming or math.

✅ Usage: Used in math equations or coding tutorials.

🔹 Example:


<p>The formula for area is <var>πr²</var></p>

✅ Key Points:

Usually displayed in italics.

📍 `<abbr>` - Abbreviation

✅ Definition: Represents an abbreviation or acronym.

✅ Usage: Shows full meaning when hovered.

🔹 Example:


<p><abbr title="HyperText Markup Language">HTML</abbr> is a markup language.</p>

✅ Key Points:

Helps with accessibility and SEO.

📍 `<strong>` - Important Text

✅ Definition: Represents strong importance (bold by default).

✅ Usage: Highlights critical words in a sentence.

🔹 Example:

 <p><strong>Warning:</strong> Do not touch the wires.</p>

✅ Key Points:

Use for important warnings or notices.

📍 `<em>` - Emphasized Text

✅ Definition: Used for emphasizing words (italic by default).

✅ Usage: Adds stress to words.

🔹 Example:

 <p>This is <em>very important</em> information.</p>

✅ Key Points:

Improves voice inflection for screen readers.

📍 `<mark>` - Highlighted Text

✅ Definition: Highlights important text (yellow by default).

✅ Usage: Used to grab attention.

🔹 Example:

 <p>Please <mark>read this carefully</mark> before proceeding.</p>

✅ Key Points:

Used for important highlights.

📍 `<del>` - Deleted Text

✅ Definition: Shows deleted text with a strike-through.

✅ Usage: Used for corrections or edits.

🔹 Example:


<p>This was <del>wrong</del> correct.</p>

✅ Key Points:

Shows content that was removed.

📍 `<ins>` - Inserted Text

✅ Definition: Shows added text with an underline.

✅ Usage: Used to show updates or edits.

🔹 Example:


<p>This is <ins>newly added</ins> content.</p>

✅ Key Points:

Helps track changes in content.

3. Grouping & Media Semantic Tags

These tags group related content and handle multimedia like images, videos, and audio. They improve SEO, readability, and accessibility.

📍 <figure> - Self-contained Content (Image/Chart/Code Snippets)

✅ Definition: Groups images, charts, code snippets, or diagrams with a caption.

✅ Usage: Helps associate an image with its description.

🔹 Example:


<figure>
    <img src="nature.jpg" alt="Beautiful Nature">
    <figcaption>Nature is always beautiful.</figcaption>
</figure>

✅ Key Points:

<figcaption> is optional and provides a caption.
Improves SEO and screen reader accessibility.

📍 <figcaption> - Caption for <figure>

✅ Definition: Provides a description or title for content inside <figure>.

✅ Usage: Used inside <figure> to describe the content.

🔹 Example:


<figure>
    <img src="car.jpg" alt="A red sports car">
    <figcaption>A stylish red sports car.</figcaption>
</figure>

✅ Key Points:

Always use it inside <figure>.

📍 <picture> - Responsive Images

✅ Definition: Helps display different images for different screen sizes.

✅ Usage: Used for responsive design.

🔹 Example:


<picture>
    <source srcset="small.jpg" media="(max-width: 600px)">
    <source srcset="large.jpg" media="(min-width: 601px)">
    <img src="default.jpg" alt="Default Image">
</picture>

✅ Key Points:

<source> chooses the best image based on screen size.
Always include a fallback <img>.

📍 <audio> - Embedding Audio

✅ Definition: Embeds audio files in a webpage.

✅ Usage: Used for background music, podcasts, or sound effects.

🔹 Example:


<audio controls>
    <source src="music.mp3" type="audio/mpeg">
    <source src="music.ogg" type="audio/ogg">
    Your browser does not support audio.
</audio>

✅ Key Points:

Use controls to add play, pause, and volume buttons.
Always provide multiple formats (.mp3, .ogg).

📍 <video> - Embedding Video

✅ Definition: Embeds video files in a webpage.

✅ Usage: Used for tutorials, clips, or background videos.

🔹 Example:


<video width="320" height="240" controls>
    <source src="video.mp4" type="video/mp4">
    <source src="video.ogg" type="video/ogg">
    Your browser does not support video.
</video>

✅ Key Points:

Use controls for play/pause buttons.
Add multiple formats for better support.

📍 <source> - Alternative Media Sources

✅ Definition: Provides alternative media sources for <picture>, <audio>, and <video>.

✅ Usage: Used inside <picture>, <audio>, or <video> to support different file types.

🔹 Example:


<audio controls>
    <source src="audio.mp3" type="audio/mpeg">
    <source src="audio.ogg" type="audio/ogg">
</audio>

✅ Key Points:

Helps provide backup formats for media.

📍 <track> - Subtitles and Captions for Video

✅ Definition: Adds subtitles, captions, or descriptions to <video>.

✅ Usage: Improves accessibility for deaf users.

🔹 Example:


<video controls>
    <source src="movie.mp4" type="video/mp4">
    <track src="subtitles.vtt" kind="subtitles" srclang="en" label="English">
</video>

✅ Key Points:

kind="subtitles" specifies that it's a subtitle file.
Use .vtt (WebVTT format) for subtitles.

4. List Semantic Tags

Lists are used to organize content in an ordered or unordered way. They help with readability, structure, and accessibility.

📍 <ul> - Unordered List

✅ Definition: Creates a bulleted list.

✅ Usage: Used when the order of items does not matter.

🔹 Example:


<ul>
    <li>Apples</li>
    <li>Bananas</li>
    <li>Oranges</li>
</ul>

✅ Key Points:

Each item in the list is inside <li> (list item).
Browser automatically adds bullets.

📍 <ol> - Ordered List

✅ Definition: Creates a numbered list.

✅ Usage: Used when the order of items matters (like steps or rankings).

🔹 Example:

 <ol>
    <li>Wake up</li>
    <li>Brush your teeth</li>
    <li>Have breakfast</li>
</ol>

✅ Key Points:

Items are numbered automatically (1, 2, 3…).
You can change the numbering style using the type attribute:
```
<ol type="A">
    <li>Item 1</li>
    <li>Item 2</li>
</ol>
```
✅ Output: A. Item 1, B. Item 2…

📍 <li> - List Item

✅ Definition: Represents a single item in <ul> or <ol>.

✅ Usage: Used inside unordered (<ul>) or ordered (<ol>) lists.

🔹 Example:


<ul>
    <li>HTML</li>
    <li>CSS</li>
    <li>JavaScript</li>
</ul>

✅ Key Points:

Must always be inside <ul> or <ol>.

📍 <dl> - Description List

✅ Definition: Creates a list of terms and descriptions.

✅ Usage: Used for glossaries, FAQs, or key-value pairs.

🔹 Example:


<dl>
    <dt>HTML</dt>
    <dd>HyperText Markup Language</dd>

    <dt>CSS</dt>
    <dd>Cascading Style Sheets</dd>
</dl>

✅ Key Points:

<dt> = Term (word or phrase)
<dd> = Description (explanation of the term)

📍 <dt> - Definition Term

✅ Definition: Represents the term (title or keyword) in a description list.

✅ Usage: Used inside <dl> before <dd>.

🔹 Example:


<dt>Python</dt>
<dd>A popular programming language.</dd>

✅ Key Points:

Must be inside <dl>.

📍 <dd> - Definition Description

✅ Definition: Represents the description or explanation of a term.

✅ Usage: Used after <dt>.

🔹 Example:


<dl>
    <dt>JavaScript</dt>
    <dd>A language used for web development.</dd>
</dl>

✅ Key Points:

Must be inside <dl> after <dt>.

📌 Comparison of List Types

Tag	Type of List	Uses
`<ul>`	Unordered (bullets)	Shopping lists, menus
`<ol>`	Ordered (numbers)	Steps, rankings, instructions
`<dl>`	Description list	Glossaries, FAQs

5. Table Semantic Tags

Tables are used to organize data in rows and columns. They are useful for reports, pricing tables, and structured content.

📍 <table> - Table Container

✅ Definition: Defines a table in HTML.

✅ Usage: Used to display tabular data.

🔹 Example:


<table border="1">
    <tr>
        <th>Name</th>
        <th>Age</th>
    </tr>
    <tr>
        <td>John</td>
        <td>25</td>
    </tr>
</table>

✅ Key Points:

<table> is the main container.
The border attribute adds a visible border (for learning).
<tr> (table row), <th> (header cell), and <td> (data cell) are used inside.

📍 <thead> - Table Header Section

✅ Definition: Groups the header rows of a table.

✅ Usage: Used to separate headers from data.

🔹 Example:


<table border="1">
    <thead>
        <tr>
            <th>Name</th>
            <th>Age</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>Alice</td>
            <td>22</td>
        </tr>
    </tbody>
</table>

✅ Key Points:

Helps organize the table structure.
Works with <tbody> and <tfoot>.

📍 <tbody> - Table Body Section

✅ Definition: Groups the main data of the table.

✅ Usage: Used to separate table content from headers/footers.

🔹 Example:

 <tbody>
    <tr>
        <td>Bob</td>
        <td>30</td>
    </tr>
</tbody>

✅ Key Points:

Only contains table rows (<tr>).

📍 <tfoot> - Table Footer Section

✅ Definition: Groups the footer content of a table.

✅ Usage: Used for totals, summaries, or extra information.

🔹 Example:


<tfoot>
    <tr>
        <td colspan="2">Total: 2 entries</td>
    </tr>
</tfoot>

✅ Key Points:

Used for summary rows.
colspan="2" makes one cell span two columns.

📍 <tr> - Table Row

✅ Definition: Represents a row in the table.

✅ Usage: Contains header (<th>) or data (<td>) cells.

🔹 Example:


<tr>
    <td>Sam</td>
    <td>28</td>
</tr>

✅ Key Points:

A table must have at least one row.

📍 <td> - Table Data Cell

✅ Definition: Represents a single data cell.

✅ Usage: Used inside <tr> to hold table data.

🔹 Example:


<td>Emma</td>

✅ Key Points:

Used to store regular data.

📍 <th> - Table Header Cell

✅ Definition: Defines a header cell.

✅ Usage: Used inside <tr> in <thead>.

🔹 Example:


<th>City</th>

✅ Key Points:

Text is bold and centered by default.

📍 <caption> - Table Title

✅ Definition: Adds a title to the table.

✅ Usage: Describes the purpose of the table.

🔹 Example:


<table border="1">
    <caption>Student Information</caption>
    <tr>
        <th>Name</th>
        <th>Age</th>
    </tr>
</table>

✅ Key Points:

Always placed inside <table>, before <tr>.

📌 Full Table Example


<table border="1">
    <caption>Employee Details</caption>
    <thead>
        <tr>
            <th>Name</th>
            <th>Position</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>John</td>
            <td>Manager</td>
        </tr>
        <tr>
            <td>Lisa</td>
            <td>Developer</td>
        </tr>
    </tbody>
    <tfoot>
        <tr>
            <td colspan="2">Total Employees: 2</td>
        </tr>
    </tfoot>
</table>

✅ Key Points:

Table is well-structured (Header, Body, Footer).
colspan="2" spans across 2 columns.

6. Form Semantic Tags

Forms are used to collect user input like login details, search queries, or contact information.

📍 <form> - Form Container

✅ Definition: The main container for user input fields.

✅ Usage: Used to group all form elements.

🔹 Example:


<form action="/submit" method="POST">
    <label for="name">Name:</label>
    <input type="text" id="name" name="name">
    <button type="submit">Submit</button>
</form>

✅ Key Points:

action="/submit" → Sends data to the server.

- `method="POST"` → Sends data securely.

📍 <label> - Input Label

✅ Definition: Adds a text label for an input field.

✅ Usage: Helps with accessibility and usability.

🔹 Example:


<label for="email">Email:</label>
<input type="email" id="email" name="email">

✅ Key Points:

for="email" should match id="email".

📍 <input> - Input Field

✅ Definition: A single-line user input field.

✅ Usage: Used for text, numbers, passwords, etc.

🔹 Example:


<input type="text" name="username">

✅ Common type values:

Type	Usage
`text`	Regular text input
`email`	Email validation
`password`	Hidden characters
`number`	Numeric input
`checkbox`	Multiple-choice selection
`radio`	Single-choice selection

📍 <button> - Clickable Button

✅ Definition: A clickable button.

✅ Usage: Used to submit forms or trigger actions.

🔹 Example:

 <button type="submit">Submit</button>

✅ Key Points:

type="submit" submits the form.
type="button" does nothing by default.

📍 <select> - Dropdown List

✅ Definition: Creates a dropdown menu.

✅ Usage: Used when users select from options.

🔹 Example:


<label for="country">Choose a country:</label>
<select id="country" name="country">
    <option value="us">USA</option>
    <option value="uk">UK</option>
</select>

✅ Key Points:

<option> defines each choice.
value="us" is sent to the server.

📍 <textarea> - Multi-line Textbox

✅ Definition: A large input box for long text.

✅ Usage: Used for comments or messages.

🔹 Example:


<textarea name="message" rows="4" cols="30">Type here...</textarea>

✅ Key Points:

rows and cols control the size.

📍 <fieldset> - Group Form Elements

✅ Definition: Groups related inputs.

✅ Usage: Used for better organization.

🔹 Example:


<fieldset>
    <legend>Personal Info</legend>
    <label>Name: <input type="text"></label>
</fieldset>

✅ Key Points:

Improves form structure.

📍 <legend> - Fieldset Title

✅ Definition: Adds a title for <fieldset>.

✅ Usage: Helps describe the group of inputs.

🔹 Example:


<legend>Contact Details</legend>

✅ Key Points:

Always placed inside <fieldset>.

📍 <datalist> - Auto-Suggestions

✅ Definition: Provides predefined suggestions.

✅ Usage: Used for quick input selection.

🔹 Example:


<input list="colors">
<datalist id="colors">
    <option value="Red">
    <option value="Blue">
</datalist>

✅ Key Points:

Users can type or select from options.

📍 <output> - Display Calculation Results

✅ Definition: Displays calculated values.

✅ Usage: Used for dynamic form outputs.

🔹 Example:


<output>50</output>

✅ Key Points:

Often used with JavaScript.

📍 <progress> - Progress Bar

✅ Definition: Shows progress percentage.

✅ Usage: Used for loading indicators.

🔹 Example:


<progress value="50" max="100"></progress>

✅ Key Points:

value="50" shows progress out of max="100".

📍 <meter> - Measurement Bar

✅ Definition: Displays a value in a known range.

✅ Usage: Used for performance levels.

🔹 Example:


<meter value="7" min="0" max="10"></meter>

✅ Key Points:

Good for battery life, scores, or ratings.

📌 Full Form Example


<form action="/submit" method="POST">
    <fieldset>
        <legend>Signup Form</legend>

        <label for="name">Name:</label>
        <input type="text" id="name" name="name">

        <label for="email">Email:</label>
        <input type="email" id="email" name="email">

        <label for="age">Age:</label>
        <input type="number" id="age" name="age">

        <label for="country">Country:</label>
        <select id="country" name="country">
            <option value="us">USA</option>
            <option value="uk">UK</option>
        </select>

        <label for="message">Message:</label>
        <textarea id="message" name="message" rows="4"></textarea>

        <button type="submit">Submit</button>
    </fieldset>
</form>

✅ Key Points:

Uses multiple input types.

- Well-structured with `<fieldset>` and `<legend>`.

🟢 7. Other Semantic Tags

These tags add meaning and functionality to content, making pages more interactive and accessible.

📍 <details> - Expandable Content

✅ Definition: Creates a collapsible section.

✅ Usage: Used for FAQs, extra info, or hidden content.

🔹 Example:


<details>
    <summary>What is HTML?</summary>
    <p>HTML stands for HyperText Markup Language.</p>
</details>

✅ Key Points:

Clicking <summary> toggles visibility.
Can be used for FAQ sections.

📍 <summary> - Details Title

✅ Definition: Defines a clickable heading for <details>.

✅ Usage: Used to describe expandable content.

🔹 Example:

 <summary>Click to reveal more</summary>

✅ Key Points:

Always placed inside <details>.

📍 <dialog> - Pop-up Box

✅ Definition: Creates a modal (popup) window.

✅ Usage: Used for alerts, confirmations, or messages.

🔹 Example:


<dialog id="myDialog">
    <p>Welcome to my website!</p>
    <button onclick="this.parentElement.close()">Close</button>
</dialog>

<button onclick="document.getElementById('myDialog').showModal()">Open Dialog</button>

✅ Key Points:

showModal() → Opens the dialog as a popup.

- `close()` → Closes the popup.

📌 Full Example with All Tags


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Other Semantic Tags</title>
</head>
<body>

    <h2>Expandable Content</h2>
    <details>
        <summary>What is JavaScript?</summary>
        <p>JavaScript is a programming language for web development.</p>
    </details>

    <h2>Modal Dialog</h2>
    <dialog id="infoDialog">
        <p>This is a popup message.</p>
        <button onclick="this.parentElement.close()">Close</button>
    </dialog>
    <button onclick="document.getElementById('infoDialog').showModal()">Open Popup</button>

</body>
</html>

✅ Key Points:

<details> and <summary> create an interactive expandable section.
<dialog> is used for popup messages.

Marquee in HTML

Definition:

The <marquee> tag is used to create scrolling text or images. However, it is deprecated in HTML5. Instead, CSS animations should be used.

Attributes:

direction: Specifies the scroll direction (left, right, up, down).
behavior: Defines the scrolling type (scroll, slide, alternate).
scrollamount: Controls the speed of the scrolling.
loop: Specifies the number of times the marquee should loop.

Example (Deprecated Method):

<marquee bgcolor="green" direction="right">Welcome to HTML</marquee>

Example (Modern CSS Method):

<div style="background-color: green; overflow: hidden">
  <div class="marquee">Welcome to HTML</div>
</div>
<style>
  .marquee {
    width: 150px;
    padding: 10px;
    white-space: nowrap;
    animation: scroll 10s linear infinite;
  }
  @keyframes scroll {
    0% { transform: translateX(100%); }
    100% { transform: translateX(-100%); }
  }
</style>

<details> and <summary>

Definition:

The <details> tag is used to create a collapsible content section.
The <summary> tag provides a heading for the collapsible section.

Example:

<details>
  <summary>What is HTML?</summary>
  <p>HTML stands for Hypertext Markup Language.</p>
</details>

<dialog> Tag

Definition:

The <dialog> element is used to create modal dialogs in HTML.

Example:

<button onclick="document.getElementById('modal').show()">Show Dialog</button>
<dialog id="modal">
  <h3>Sample Heading</h3>
  <p>This is a sample dialog box.</p>
  <button onclick="document.getElementById('modal').close()">Close</button>
</dialog>

HTML Entities & Symbols

Definition:

HTML entities are special codes used to display reserved or special characters in HTML.

Common Entities:

Entity Code	Symbol
`©`	©
`™`	™
`®`	®
`<`	<
`>`	>
`&`	&

Example:

<p>&copy; 2025 YourWebsite &trade; &reg; </p>

Emojis:

Emoji Code	Emoji
`😊`	😊
`👋`	👋
`😄`	😄

<p>Hello! &#x1F44B; Welcome to my site! 😊</p>

HTML File Paths

Definition:

File paths specify the location of files in a website.

Types of File Paths:

Relative Path: References files within the same directory.
Absolute Path: References files using a full URL.
Root-relative Path: Starts from the root directory (/).

Examples:

Relative Path:

<img src="./photo.jpg" alt="Sample" width="300px" />

Absolute Path:

<img src="https://example.com/image.jpg" alt="Sample" width="300px" />

Root-relative Path:

<img src="/images/sample.jpg" alt="Sample" width="300px" />

HTML Image Handling

Definition:

The <img> tag is used to display images in HTML.

Attributes:

src: Specifies the image source.
alt: Provides alternative text if the image fails to load.
width & height: Set the size of the image.
loading: Specifies lazy loading for images (lazy, eager).

Example:

<img src="https://cdn.britannica.com/34/235834-050-C5843610/cat.jpg" alt="Cat" width="300px" loading="lazy" />

Character Sets in HTML

Definition:

A character set in HTML defines how characters are encoded and displayed in web browsers.

Common Character Sets:

Charset	Description
UTF-8	Universal character set (supports most languages)
ISO-8859-1	Western European languages
ASCII	Basic English characters

Setting Character Encoding:

The <meta charset> tag specifies the character encoding of an HTML document.

Example:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Character Encoding</title>
</head>
<body>
    <p>© 2025 - Welcome to my website!</p>
</body>
</html>

Why Use UTF-8?

It supports all languages and special characters.
It prevents display issues with non-English characters.

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MERN - Html (Day 7)

- Usually contains branding, logo, and navigation links.

📍 <nav> - Navigation Links

📍 <main> - Main Content Area

📍 <article> - Independent Content

📍 <section> - Thematic Section

📍 <aside> - Sidebar Content]

- Placed beside articles or main sections.

📍 <footer> - Bottom Section

- Contains useful links, copyright, and credits.

📍 <h1> to <h6> - Headings

📍 <p> - Paragraph

📍 <blockquote> - Quoting a Block of Text

- Use <cite> inside it to give source information.

📍 <cite> - Citing a Source

📍 <q> - Short Inline Quote

📍 <time> - Representing Date and Time

📍 <address> - Contact Information

📍 <pre> - Preformatted Text

📍 <code> - Inline Code

📍 <kbd> - Keyboard Input

📍 <samp> - Sample Output

📍 <var> - Variable in Programming

📍 <abbr> - Abbreviation

📍 <strong> - Important Text

📍 <em> - Emphasized Text

📍 <mark> - Highlighted Text

📍 <del> - Deleted Text

📍 <ins> - Inserted Text

- method="POST" → Sends data securely.

- Well-structured with <fieldset> and <legend>.

- close() → Closes the popup.

Definition:

Attributes:

Example:

Common Entities:

Examples:

Definition:

Example:

📍 `<nav>` - Navigation Links

📍 `<main>` - Main Content Area

📍 `<article>` - Independent Content

📍 `<section>` - Thematic Section

📍 `<aside>` - Sidebar Content]

📍 `<footer>` - Bottom Section

📍 `<h1>` to `<h6>` - Headings

📍 `<p>` - Paragraph

📍 `<blockquote>` - Quoting a Block of Text

- Use `<cite>` inside it to give source information.

📍 `<cite>` - Citing a Source

📍 `<q>` - Short Inline Quote

📍 `<time>` - Representing Date and Time

📍 `<address>` - Contact Information

📍 `<pre>` - Preformatted Text

📍 `<code>` - Inline Code

📍 `<kbd>` - Keyboard Input

📍 `<samp>` - Sample Output

📍 `<var>` - Variable in Programming

📍 `<abbr>` - Abbreviation

📍 `<strong>` - Important Text

📍 `<em>` - Emphasized Text

📍 `<mark>` - Highlighted Text

📍 `<del>` - Deleted Text

📍 `<ins>` - Inserted Text

- `method="POST"` → Sends data securely.

- Well-structured with `<fieldset>` and `<legend>`.

- `close()` → Closes the popup.