Python Basics

Fundamentals of Python programming: variables, data types, input/output, and basic syntax - with practical examples.

1. First Line of Python - Printing Output

The print() function displays text or values on the screen.

print("Hello Python!")
print("Learning step by step")
print("Line A\n")
print("Line B")

Output

Hello Python!
Learning step by step
Line A

Line B

\n creates a new line.

2. Variables - Storing Information

Variables are containers for values. You assign them using =.

student = "Maria"
age = 19
city = "Mombasa"

print(student, "is", age, "years old and lives in", city)

Output

Maria is 19 years old and lives in Mombasa

Variables can be updated or replaced.

points = 40
print("Points before:", points)

points = 55   # replace old value
print("Points after:", points)

points = points + 15
print("Points plus 15:", points)

Output

Points before: 40
Points after: 55
Points plus 15: 70

3. Style Rules Readable Code

Use descriptive variable names and keep track of updates.

name = "James Mwangi"
age = 30
track = "Web Development"
sessions_left = 5

print(name, "is", age, "years old.", "Track:", track, "Sessions left:", sessions_left)

sessions_left = sessions_left - 1
print("Sessions left:", sessions_left)

Output

James Mwangi is 30 years old. Track: Web Development Sessions left: 5
Sessions left: 4

4. Data Types - Kinds of Values

Python has built-in data types:

str → text (strings, always in quotes)

int → whole numbers

float → decimal numbers

bool → logical values (True/False)

title = "Python Basics"   # str
year = 2026               # int
price = 99.99             # float
is_published = False      # bool

print(type(title))
print(type(year))
print(type(price))
print(type(is_published))

Output

<class 'str'>
<class 'int'>
<class 'float'>
<class 'bool'>

Strings that look like numbers ("10") are still text, not integers.

5. Input - Getting User Data

The input() function lets users type values. By default, it returns a string.

name = input("Enter your name: ")
print("Hello,", name)
print("Welcome to Python Basics")

Output

Enter your name: Kelvin
Hello, Kelvin
Welcome to Python Basics

6. Convert input to numbers using int() or float().

age = int(input("Enter your age: "))
print("You are", age, "years old")
print("Next year you will be", age + 1)

Output

Enter your age: 21
You are 21 years old
Next year you will be 22

7. f-Strings - Formatted Output

f-strings make it easy to embed variables inside text.

name = "Sophia"
age = 22
city = "Kisumu"
balance = 3200.50

print(f"Name: {name} Age: {age} City: {city} Balance: {balance}")
print(f"Next year {name} will be {age + 1} years old")

Output

Name: Sophia Age: 22 City: Kisumu Balance: 3200.5
Next year Sophia will be 23 years old

Practical Examples - Applying the Basics
Example 1: Simple Calculator with VAT

price = int(input("Enter the price (Ksh): "))
quantity = int(input("Enter quantity: "))

subtotal = price * quantity
vat = subtotal * 0.16
total = subtotal + vat

print(f"Item price: Ksh {price}")
print(f"Quantity:   {quantity}")
print(f"Subtotal:   Ksh {subtotal}")
print(f"VAT (16%):  Ksh {vat}")
print(f"Total:      Ksh {total}")

Output

Enter the price (Ksh): 200
Enter quantity: 3
Item price: Ksh 200
Quantity:   3
Subtotal:   Ksh 600
VAT (16%):  Ksh 96.0
Total:      Ksh 696.0

Example 2: Bus Ticket Booking

print("=" * 35)
print("           BUS TICKET BOOKING")
print("=" * 35)

passenger_name = input("Enter passenger name: ")
route = input("Enter route: ")
fare = int(input("Enter fare (Ksh): "))
booking_fee = 15

print("=" * 35)
print("           TICKETING")
print("=" * 35)
print(f"Passenger      : {passenger_name}")
print(f"Route          : {route}")
print(f"Fare           : Ksh{fare}")
print(f"Booking fee    : Ksh{booking_fee}")
print("-" * 35)
print(f"Total          : Ksh{fare + booking_fee}")
print("=" * 35)
print("         THANK YOU FOR BOOKING")
print("=" * 35)

Output

Enter passenger name: Brian
Enter route: Nakuru
Enter fare (Ksh): 120
Passenger      : Brian
Route          : Nakuru
Fare           : Ksh120
Booking fee    : Ksh15
Total          : Ksh135
THANK YOU FOR BOOKING

Example 3: School Grade Calculator

print("=" * 38)
print("     SCHOOL GRADE CALCULATOR")
print("=" * 38)

student_name = input("Enter Student name: ")
subject = input("Enter subject: ")
print(f"Enter 3 test scores for {student_name}:")
test_1 = int(input("  Test 1: "))
test_2 = int(input("  Test 2: "))
test_3 = int(input("  Test 3: "))

average = (test_1 + test_2 + test_3) / 3

print("=" * 38)
print(f"   REPORT: {student_name}")
print("=" * 38)
print(f"Subject: {subject}")
print(f"Average Score: {average}")

Output

Enter Student name: Lydia
Enter subject: English
Enter 3 test scores for Lydia:
  Test 1: 65
  Test 2: 70
  Test 3: 80

REPORT: Lydia
Subject: English
Average Score: 71.666...

Conclusion

print() displays output.

Variables store values that can be updated.

Python has built-in data types (str, int, float, bool).

input() gets user input, and you can convert it to numbers.

f-strings make output formatting easier.