HTTP Request Methods and Status Codes

HTTP defines several request methods, each serving a specific purpose in web communication. GET requests retrieve data from the server and should not modify server state. POST requests submit data to be processed, often resulting in state changes or resource creation. PUT requests update existing resources, while DELETE requests remove resources. Other methods like HEAD, OPTIONS, PATCH, and CONNECT serve specialized purposes in web applications and APIs.

Status codes in HTTP responses indicate the result of the request processing. These three-digit codes fall into five categories: informational responses (100-199), successful responses (200-299), redirections (300-399), client errors (400-499), and server errors (500-599). Common codes include 200 OK for successful requests, 404 Not Found for missing resources, 301 Moved Permanently for redirections, and 500 Internal Server Error for server-side problems. Understanding these codes helps diagnose issues and build robust web applications.

Headers play a crucial role in HTTP communication, carrying metadata about requests and responses. Request headers might include User-Agent (identifying the browser), Accept (specifying acceptable content types), Cookie (sending stored data), and Host (identifying the target server). Response headers include Content-Type (describing the response format), Set-Cookie (storing data on the client), Cache-Control (defining caching behavior), and Server (identifying server software). These headers enable sophisticated features like content negotiation, authentication, and caching.