17.1. Introduction

In this chapter, we discuss the specialized software—called a web server—that responds to client requests (typically from a web browser) by providing resources such as XHTML documents. For example, when users enter a Uniform Resource Locator (URL) address, such as www.deitel.com, into a web browser, they’re requesting a specific document from a web server. The web server maps the URL to a resource on the server (or to a file on the server’s network) and returns the requested resource to the client. During this interaction, the web server and the client communicate using the platform-independent Hypertext Transfer Protocol (HTTP), a protocol for transferring requests and files over the Internet or a local intranet.

We also discuss two web servers—the open source Apache HTTP Server and Microsoft’s Internet Information Services Express (IIS Express)—that you can install on your own computer for testing your web pages and web applications.