How to read an HTTP request — headers, body, methods

HTTP is the protocol the web runs on. Every time you load a page, call an API, or submit a form, you're making HTTP requests. Understanding what's actually in them makes building and debugging web things significantly easier.

The structure of a request

An HTTP request has three parts: the request line, headers, and optionally a body.

POST /api/users HTTP/1.1
Host: api.example.com
Content-Type: application/json
Authorization: Bearer eyJhbGc...
Content-Length: 42

{"name": "Theo", "email": "me@example.com"}

Methods

The method tells the server what you want to do:

• GET — retrieve something. No body. Safe to repeat.
• POST — create something. Has a body. Not safe to repeat.
• PUT — replace something entirely.
• PATCH — update part of something.
• DELETE — remove something.

Headers

Headers are key-value pairs that provide metadata about the request. The important ones:

• Content-Type — what format the body is in. application/json for JSON, multipart/form-data for file uploads.
• Authorization — credentials. Usually Bearer TOKEN for API auth.
• Accept — what format the client wants the response in.
• Host — which domain the request is for. Required in HTTP/1.1.

Status codes in responses

Responses come back with a status code that tells you what happened:

• 2xx — success. 200 OK, 201 Created, 204 No Content.
• 3xx — redirect. 301 Moved Permanently, 302 Found.
• 4xx — client error. 400 Bad Request, 401 Unauthorized, 403 Forbidden, 404 Not Found.
• 5xx — server error. 500 Internal Server Error, 502 Bad Gateway, 503 Service Unavailable.

Seeing real requests

Open browser dev tools, go to the Network tab, and reload a page. Every HTTP request the page makes is listed there — click one to see the full headers, body, and response. This is the fastest way to understand what's actually happening between a browser and a server.