Chapter 3. Sending Requests Using HTTP
Various protocols are used for communication over the World Wide Web, perhaps the most important being HTTP, the protocol that is also fundamental to Ajax applications. This lesson introduces the HTTP protocol and shows how it is used to request and receive information.
HTTP or Hypertext Transfer Protocol is the main protocol of the World Wide Web. When you request a web page by typing its address into your web browser, that request is sent using HTTP. The browser is an HTTP client, and the web page server is (unsurprisingly) an HTTP server.
In essence, HTTP defines a set of rules regarding how messages and other data should be formatted and exchanged between servers and browsers.