HTTP

The Hypertext Transfer Protocol (HTTP) is the underlying protocol used by the Web, and it runs by default on TCP port 80. When you enter "http://" at the beginning of a Web server's IP address, you are identifying how messages are formatted and transmitted, requesting and responding to the transfer of HTML-formatted files. HTTP defines what actions Web servers and browsers should take in response to various commands.

HTTP has a general weakness in its handling of Web pages: it relays commands executed by users without reference to any commands previously executed. The problem with this is that Web designers continue to design more complex and truly interactive Web pages. HTTP is pretty dumb when it comes to remembering what people have done on a Web site. Luckily for Web designers everywhere, other technologies exist to help HTTP relay commands and thus support more-interactive, intelligent Web sites. These technologies include JavaScript/AJAX, server-side scripting, Adobe Flash, and cookies.