Client-Server architecture

The HTTP protocol is based on a request/response paradigm. The communication generally takes place over a TCP/IP connection on the Internet. The default port is 80, but other ports can be used. This does not preclude the HTTP/1.0 protocol from being implemented on top of any other protocol on the Internet, so long as reliability can be guaranteed. A requesting program (a client) establishes a connection with a receiving program (a server) and sends a request to the server in the form of a request method, URI, and protocol version, followed by a message containing request modifiers, client information, and possible body content. The server responds with a status line, including its protocol version and a success or error code, followed by a message containing server information, entity metainformation, and possible body content.