Part 2 of the Backend from First Principles series

After understanding the foundational concepts of backend engineering, it's time to dive into the protocol that powers the web: HTTP (HyperText Transfer Protocol). This is where everything truly begins for a backend engineer.

What is HTTP?

HTTP is the medium through which the browser talks to the server. It's the communication protocol that enables the request-response cycle between clients and servers, forming the backbone of web applications.

At its core, HTTP operates on two fundamental principles:

1. Stateless Nature

HTTP is stateless - meaning it has no memory of past interactions. The server doesn't remember previous requests, and each request must include all the necessary data for processing.

This has profound implications:

• Each request must be self-contained with all required information
• Session management requires additional mechanisms (cookies, tokens, etc.)
• Scalability improves since servers don't need to maintain state

2. Client-Server Model

HTTP uses a classic client-server architecture where:

• Client initiates requests (typically a browser or API consumer)
• Server processes requests and sends responses
• Communication is always initiated by the client to get some response from the server

The Anatomy of HTTP Messages

HTTP Request Structure

When a client sends a request, it includes several components: