Understanding Web and Internet Fundamentals

Introduction

Behind every website you visit, video you stream, or message you send, there’s a sophisticated chain of communication happening that you never see. Understanding how servers, DNS, protocols, ports, and other internet concepts and technologies work together isn’t just for developers, it’s like learning the basic mechanics of a car. You don’t need to be a mechanic to drive, but knowing what’s under the hood helps you make better decisions and troubleshoot when things go wrong.

This guide breaks down the essential building blocks of the internet and web, explaining not just what they are, but how they work together to make our connected world possible.

The Foundation: Servers and Clients

At its core, the internet operates on a simple relationship: one computer asks for something, and another computer provides it. The computer doing the asking is called a client (the browser in your phone or computer), and the computer providing the resource is called a server.

Source: O’Reilly Media

A server isn’t necessarily a massive machine in a data center, it’s any computer configured to respond to requests. Your laptop could be a server if you set it up that way. What makes something a server is its role, not its hardware.

When you type “google.com” into your browser, you’re using a client to request Google’s homepage from their servers. The server processes your request and sends back the HTML, CSS, and JavaScript that your browser assembles into the page you see.

How Computers Find Each Other

IP Addresses

Every device connected to the internet needs an address, just like every house needs a street address for mail delivery. That’s where IP addresses come in. An IP address is a unique numerical identifier like 192.168.1.1 (IPv4) or the longer 2001:0db8:85a3:0000:0000:8a2e:0370:7334 (IPv6).

Think of it this way: if the internet is a massive city, IP addresses are the exact coordinates of every building. But there’s a problem, we humans aren’t great at remembering long strings of numbers.

Domain Names and DNS

This is where domain names and the Domain Name System (DNS) save the day. A domain name like amazon.com is simply a human-friendly alias for an IP address. When you type a domain name, your computer asks a DNS server, "What's the IP address for this domain?" The DNS server responds with the actual IP address, and your computer uses that to connect.

DNS is often called the “phone book of the internet,” but it’s more like a constantly updated GPS system that helps you find the right destination every time.

Here’s a fun exercise to try out; Type 216.58.223.238 in your browser and see where that leads you.

URLs: The Complete Address

A URL (Uniform Resource Locator) is the full address you see in your browser’s address bar. It contains several parts:

• Protocol: https:// tells your browser how to communicate
• Domain: bbc.com identifies the server
• Port: :443 (often hidden) specifies which service to use
• Path: /sport/football points to a specific resource

So https://bbc.com:443/sport/football is a complete instruction set for retrieving football content from BBC’s server.

Ports: Multiple Services, One Address

Here’s where things get interesting. A single server with one IP address can run dozens of different services simultaneously; a web server, an email server, a file transfer server, and more. How does incoming traffic know which service to reach? Ports.

Think of an IP address as a large apartment building, and ports as individual apartment numbers. Port numbers range from 0 to 65,535, and certain numbers are standardized for specific services:

• Port 80: HTTP (unsecured web traffic)
• Port 443: HTTPS (secured web traffic)
• Port 25: SMTP (email sending)
• Port 22: SSH (secure remote access)
• Port 3306: MySQL database

When you visit a website, your browser automatically connects to port 443 (for HTTPS) or port 80 (for HTTP) unless you specify otherwise. This combination of IP address and port number creates a socket which is a unique endpoint for communication.

Protocols: The Language of the Internet

Computers need to speak the same language to understand each other. Protocols are simply agreed-upon rules and standards for communication. These protocols define everything from how data is packaged and addressed to how errors are handled and connections are maintained.

When you send data, it doesn’t travel as one piece. Instead, it passes through multiple layers, with each adding its own header information in a process called encapsulation.

Data movement across a network follows the Open Systems Interconnection (OSI) Model, a seven-layer framework. As data travels down the layers (encapsulation), each layer adds a header with its specific control information (e.g., ports at Transport layer, IP addresses at Network layer). At the destination, the process reverses (decapsulation).

Source: NetBeez

At the Transport Layer (Layer 4) of the OSI model, data is managed by two primary protocols: TCP and UDP.

TCP: The Reliable Data Transfer Protocol

TCP (Transmission Control Protocol) is a connection-oriented protocol that prioritizes reliability over speed. Before any data is transmitted, TCP performs a three-way handshake (SYN, SYN-ACK, ACK) to establish a connection between client and server. It then breaks data into segments, numbers each one sequentially, and transmits them. The receiving end sends acknowledgments (ACKs) for received segments, and TCP retransmits any that go missing or arrive corrupted.

TCP also handles congestion control, automatically adjusting transmission rates based on network conditions. TCP is used for web pages (HTTP/HTTPS), email (SMTP, IMAP), file transfers (FTP), and any application where data integrity is critical.

UDP: The Fast Data Transfer Protocol

UDP (User Datagram Protocol) is a fast, minimalist transport protocol used on the internet. It works by sending small units of data, called datagrams, to a destination without setting up a formal connection first (it’s connectionless).

Because of its speed, UDP is perfect for time-sensitive applications where a little lost data is better than waiting to recover it. UDP is used in video streaming, DNS queries and online gaming.

Source: Storm Streaming

HTTP: Web Traffic

HTTP (Hypertext Transfer Protocol) is an application-layer (layer 7) protocol that defines the structure of requests and responses between web clients and servers. It’s a stateless protocol, meaning each request-response pair is independent i.e., the server doesn’t inherently remember previous interactions.

An HTTP request consists of a request line (method, URI, and HTTP version), headers (metadata like Content-Type, User-Agent, and Accept), and an optional body. Common HTTP methods include:

• GET: Retrieve a resource
• POST: Submit data to be processed
• PUT: Update or create a resource
• DELETE: Remove a resource
• HEAD: Retrieve headers only (useful for checking if content has changed)

The server responds with a status line (HTTP version, status code, and reason phrase), response headers, and usually a body containing the requested content. Status codes are grouped by category:

• 200–299 for success
• 300–399 for redirects
• 400–499 for client errors, (where the infamous 404 lives)
• 500–599 for server errors..

HTTPS: Secure Web Traffic

HTTPS is HTTP secured with TLS (Transport Layer Security), the successor to SSL (Secure Sockets Layer). When you connect to an HTTPS site, your browser and the server perform a TLS handshake. The server presents a digital certificate proving its identity, and both sides use a complex, slow process (asymmetric encryption, like RSA) to securely agree on a secret code, called a session key. All subsequent data (the actual website content) is encrypted using the shared session key in a faster method (symmetric encryption, like AES).

This provides three critical security properties: confidentiality (data can’t be read by eavesdroppers), integrity (data can’t be modified without detection), and authentication (you’re communicating with the real server, not an impostor).

The padlock icon 🔒 in your browser verifies that the server’s certificate is valid and trusted.

Source: Nix United

In a nutshell, HTTP is an insecure connection that can be intercepted and read by anyone, but HTTPS is HTTP secured with TLS encryption, meaning the data is scrambled and protected from eavesdroppers.

IP: Routing Protocol

IP (Internet Protocol) operates at the network layer (Layer 3) and is responsible for addressing and routing packets across networks. IP gives every device a unique IP address (its label or “street address”) and uses that address to figure out the best path for data transfer.

When you send data, IP breaks it into packets and forwards each one toward its destination. Each IP packet contains a header with source and destination IP addresses, a time-to-live (TTL) value, protocol identifier (indicating whether the payload is TCP, UDP, or something else), and other control information.

Routers read the destination address on the packet’s header to decide where to send it next (next hop). The TTL value of each packet counts down with every hop. If the TTL reaches zero, the packet is thrown away. This prevents packets from endlessly circulating the network if a routing error occurs.

IP is connectionless and unreliable by design. It makes a best-effort attempt to deliver packets but provides no guarantees. Packets might arrive out of order, get duplicated, or be dropped entirely due to network congestion or routing failures. Higher-layer protocols like TCP handle reliability concerns.

There are two versions in use: IPv4 uses 32-bit addresses (about 4.3 billion possible addresses) and is running out of available addresses, while IPv6 uses 128-bit addresses (enough for trillions of trillions of addresses) and is gradually being adopted worldwide.

The Request-Response Cycle

Let’s put it all together with what happens when you visit a website:

1. You type https://example.com/blog into your browser
2. Your browser asks a DNS server for the IP address of example.com
3. DNS responds with the IP address (e.g., 93.184.216.34)
4. Your browser establishes a TCP connection to that IP address on port 443
5. An SSL/TLS handshake encrypts the connection
6. Your browser sends an HTTP GET request for /blog
7. The server processes the request and sends back an HTTP response with the HTML content
8. Your browser receives the response, renders the page, and makes additional requests for images, stylesheets, and scripts
9. The TCP connection eventually closes

This entire process typically happens in under a second, with multiple requests happening simultaneously.

APIs and Modern Web Architecture

As the web evolved, servers started doing more than just serving HTML pages. APIs (Application Programming Interfaces) allow different programs to communicate with servers using structured requests and responses. This communication typically involves sending and receiving JSON (JavaScript Object Notation) data, which is faster and lighter than sending a full webpage.

For instance, instead of the server sending an entire blog page (with headers, footers, and sidebars), it can use an API to send only the raw content of the blog post. This data can then be used by a mobile app, a separate web application, or a browser to display the content how it needs to.

REST API

REST API (Representational State Transfer) is a popular architectural style for building APIs. It uses standard HTTP methods (GET, POST, PUT, DELETE) to perform operations on resources identified by URLs. For example:

• GET /api/users/123 retrieves user data
• POST /api/users creates a new user
• PUT /api/users/123 updates user data
• DELETE /api/users/123 deletes a user

Source: iDempiere

This approach powers most modern web applications, mobile apps, and connected services.

Network Management and Security

Firewalls

A firewall acts as a security guard, monitoring network traffic and blocking potentially harmful connections based on predefined rules. It can block specific ports, IP addresses, or types of traffic to protect servers from attacks.

Load Balancers

When a website becomes popular, one server isn’t enough. A load balancer sits in front of multiple servers and distributes incoming requests among them. If one server fails, the load balancer routes traffic to the healthy servers, ensuring the website stays online.

Proxy Servers

A proxy server acts as an intermediary between clients and servers. It can cache content to improve performance, filter requests for security, or mask the client’s IP address for privacy. Many organizations use proxy servers to control and monitor internet access.

Performance and Optimization

Several factors affect how fast and reliably data travels across the internet:

Bandwidth

Bandwidth is the maximum amount of data that can be transferred in a given time period, like the width of a highway. More bandwidth means more data can flow simultaneously.

Latency

Latency is the time it takes for data to travel from one point to another, like the speed limit on that highway. Lower latency means faster response times. Geographic distance, network congestion, and the number of intermediate routers all affect latency.

Packets

Packets are the small chunks that data gets broken into for transmission. Each packet contains both the actual data (payload) and information about where it’s going and where it came from. Breaking data into packets allows for more efficient use of network resources and better error handling.

Conclusion

The internet might seem like magic, but it’s really a carefully orchestrated system of protocols, addresses, and services working together. Servers and clients communicate through well-defined ports using agreed-upon protocols. Domain names make the internet human-friendly, while IP addresses and routing make it functional. Security layers like HTTPS protect our data, and architectural patterns like REST make building connected applications possible.

Understanding these fundamentals doesn’t just satisfy curiosity, it empowers you to troubleshoot problems, make informed decisions about web technologies, and appreciate the remarkable engineering that connects billions of devices worldwide. The next time you load a webpage in a fraction of a second, you’ll know the invisible symphony of technology making it happen.

These concepts form the foundation of everything that happens online. The internet is complex, but at its core, it’s just computers talking to each other and now you know their language.