HTTP headers are a means for a client, server, and any intermediaries to exchange information during the HTTP request-response process.
HyperText Transfer Protocol (HTTP)
The Hyper Text Transfer Protocol, is the foundation and primary means for requesting and receiving hypermedia (web-based) resources, for example HTML, images, text and media files, and is part of the internet protocol suite.
The original HTTP specifications were written in the early 1990s and evolved to newer versions of HTTP, notably HTTP/2 and HTTP/3, which are designed to be faster by reusing already open connections to request and retrieve multiple resources.
Following a client-server model, HTTP sessions are established using a TCP or UDP connection, where the client will initiate the connection and the server, optionally through intermediaries, will acknowledge and use the same connection for transmitting and receiving data (HTTP messages). The two types of HTTP messages are requests and responses.
If you are reading this in a browser, you are using HTTP to access this page.
To communicate efficiently between the client, server and intermediaries HTTP utilizes, among others:
HTTP methods are intended to cover all possible types of interaction with server-side resources.
HTTP status codes are used to indicate success, failure, and other properties about the result of an HTTP request.
A Uniform Resource Identifier (URI) is a sequence of characters that uniquely identifies a resource by location, name, or both.