HTTP (Hyper Text Transfer (or Transport) Protocol)

HTTP stands for Hyper Text Transfer (or Transport) Protocol, the most often used protocol to transfer information from World Wide Web servers to users of the Web. In other words, the Hypertext Transfer Protocol (HTTP) is the set of rules for exchanging files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. Using HTTP, two machines can communicate over a tcp/ip connection. An HTTP server is a program that sits listening on a machine's port for HTTP requests. An HTTP client opens a tcp/ip connection to the server via a socket, transmits a request for a document, then waits for a reply from the server. Once the request-reply sequence is completed, the socket is closed. That is why the HTTP protocol is called a transactional one.

Any Web server machine contains, an HTTP daemon, a program that is designed to wait for HTTP requests and handle them when they arrive. Your Web browser is actually an HTTP client, which sends requests to server machines. When the browser user enters file requests (whether by "opening" a Web file, typing in a Uniform Resource Locator, or clicking on a hypertext link) the browser builds an HTTP request and sends it to the Internet Protocol address indicated by the URL. The HTTP daemon in the destination server machine receives the request and, after any necessary processing, the requested file is returned. The latest version of HTTP is HTTP 1.1.