The HTTP Protocol (Webmaster in a Nutshell, 3rd Edition)

1.4. The HTTP Protocol

In between clients and servers is the network, which uses TCP (Transmission Control Protocol) and IP (Internet Protocol) to transmit data and find servers and clients. On top of TCP/IP, clients and servers use the HTTP protocol to communicate. Chapter 17 gives details on the HTTP protocol, which you must understand for writing CGI programs, server scripts, web administration, and just about any other part of working with a server.

What About Web Services?

"Web Services" is the name given to technologies such as SOAP and XML-RPC, which use existing Internet-related technologies (HTTP, XML, RPC) to exchange data between applications. Web services are so-called because they use the HTTP protocol, but as far as the Web is concerned, it's just another type of content. We don't cover web services in this book because they're more interesting to networked application developers than to web developers.