HTTP

The language browsers and servers use to talk: a request goes out, a response comes back.

A request-response protocol over TCP. Clients send requests with a method (GET, POST, PUT, DELETE), path, headers, and optional body; servers respond with a status code, headers, and body. Status 200 = OK, 404 = not found, 500 = server error.

Stateless application-layer protocol defined by the IETF. HTTP/1.1 uses persistent connections and pipelining; HTTP/2 multiplexes streams over a single TCP connection with binary framing; HTTP/3 runs over QUIC for lower-latency setup and head-of-line-blocking-free streams.