HTTPrequests

HTTP requests are messages sent by a client to a server using the Hypertext Transfer Protocol (HTTP) to request a resource or to perform an action. They are a fundamental part of the Web, enabling browsers and programs to communicate with web servers and APIs. A request-response cycle begins when a client issues a request and a server replies with a status code and, if appropriate, a message body.

An HTTP request consists of a request line, headers, an empty line, and an optional body. The request line contains a method, a request target (often a path and query), and the HTTP version. Headers convey metadata such as Host, User-Agent, Accept, and Content-Type. A Content-Length header is used to indicate body size when a body is present.

Common methods include GET, POST, PUT, PATCH, DELETE, HEAD, and OPTIONS. GET retrieves a resource and should be safe and idempotent; POST submits data to create or modify resources; PUT and PATCH update existing resources; DELETE removes them; HEAD fetches only headers; OPTIONS reveals supported capabilities. Requests may carry a body (notably with POST, PUT, PATCH) containing data in formats such as JSON or form-encoded data, accompanied by an appropriate Content-Type.

HTTP itself is stateless, but connections may be kept open for multiple requests. HTTP/1.1 introduced persistent connections; HTTP/2 and HTTP/3 improve performance through multiplexing and binary framing. Most traffic today is encrypted with HTTPS, which uses TLS to protect confidentiality and integrity.

HTTP requests are used by web browsers, mobile apps, and servers when interacting with RESTful or other APIs. Common development tools include curl, httpie, and fetch APIs in web browsers. Security considerations include input validation, authentication, and protection against CSRF and man-in-the-middle attacks.