Hypertext Transfer Protocol, or HTTP, is the most widely used application layer protocol in the world today. It forms the basis of the World Wide Web. Its main objective is to provide a method for the retrieval of HyperText Markup Language (HTML) and other applications from any web sites.
HTTP was first developed in the early 1990s and has been through three main versions:
- HTTP/0.9: A simplistic first implementation of the protocol that only supported the option to get a web page, rarely used today.
- HTTP/1.0: Ratified by the IETF as RFC 1945 in 1996. Keepalive Disabled by default. This version added many data fields, known as headers to the specification. This allowed for other information passing between the client and server, alongside the request and consequent page.
- HTTP/1.1: Defined in RFC 2068 by the IETF, version 1.1 implemented a number of improvements over and above the 1.0 specification. One of the main improvements of 1.1 over 1.0 was the implementation of techniques such as persistent TCP connections, pipelining, better proxy and cache control to improve performance within HTTP-based applications.