Short for Hypertext Transfer Protocol, HTTP is the protocol by which HTML files and other data are transferred across the Internet. Operating as a request-response protocol within the client-server computing model. One example of the role of http is when the client is a web browser and the server is a computer that hosts a website. In that scenario, the client web browse submits a http request message to the server, which returns a response message to the client with html files, data, and/or other content.

Designed to allow intermediary network programs and devices to enable or enhance communications between servers and clients, HTTP is an application layer protocol designed within the Internet Protocol Suite networking model, and its definition therein assumes a reliable underlying transport layer protocol. Typically, this transport layer protocol is the Transmission Control Protocol (TCP), although HTTP can use less reliable protocols like the User Data Protocol (UDP).

The initial version of HTTP used only the GET method to request a response from a server, and the only response that could be returned by the server was an HTML page. Additional methods were developed before the unveiling of the first officially documented version of the protocol, HTTP V0.9, which was released in 1991. Following the development of new features and capabilities, HTTP V1.0 was finally launched in 1996.