1.1 What Is HTTP?

HTTP is the protocol behind the World Wide Web. With every web transaction, HTTP is invoked. HTTP is behind every request for a web document or graphic, every click of a hypertext link, and every submission of a form. The Web is about distributing information over the Internet, and HTTP is the protocol used to do so.

HTTP is useful because it provides a standardized way for computers to communicate with each other. HTTP specifies how clients request data, and how servers respond to these requests. By understanding how HTTP works, you'll be able to:

• Manually query web servers and receive low-level information that typical web browsers hide from the user. With this information, you can better understand the configuration and capabilities of a particular server, and debug configuration errors with the server or programming errors in programs invoked by the web server.

• Understand the interaction between web clients (browsers, robots, search engines, etc.) and web servers.

• Streamline web services to make better use of the protocol.