What Is HTTP?
When your browser talks to a web server, they need to speak the same language. That language is HTTP — the Hypertext Transfer Protocol. It's a set of rules that defines how requests should be formatted, what information they should contain, and how responses should be structured.
Think of HTTP like the rules for exchanging formal letters. Both parties agree on conventions: where to put the address, how to format the date, what constitutes a proper greeting. Without these shared rules, communication would be chaotic and unreliable.
A Stateless Conversation
One of HTTP's most important characteristics is that it's stateless. Each request-response cycle is independent — the server doesn't automatically remember previous interactions. When you load a webpage and then click a link, the server treats the second request as if it's never heard from you before.
This might seem limiting, but it's actually a feature. Statelessness makes the web simpler and more scalable. Servers don't need to track millions of ongoing conversations. Each request contains everything needed to process it.
Of course, websites often need to remember you — for shopping carts, login sessions, and preferences. They achieve this through mechanisms like cookies and sessions, which add state on top of HTTP's stateless foundation.
Requests and Responses
HTTP defines the structure of both requests and responses. A request includes a method (like GET or POST), a path (which resource you want), headers (metadata), and sometimes a body (data you're sending).
A response includes a status code (did it work?), headers (metadata about the response), and typically a body (the actual content).
Headers: The Metadata Layer
Headers carry crucial information that isn't part of the main content. Request headers might specify what languages you accept, what browser you're using, or authentication credentials. Response headers might indicate the content type, caching rules, or security policies.
This metadata layer makes HTTP flexible enough to handle everything from simple text pages to complex web applications.
The Foundation of the Web
HTTP has evolved through several versions, with HTTP/2 and HTTP/3 adding performance improvements. But the core concept remains the same: a standardized way for clients and servers to exchange information. Every website you visit, every API you use, and every web application you interact with relies on HTTP.