How Web Servers Work

Web Servers, the Internet and HTML

Basically, a web server is any program that uses HTTP (hypertext transfer protocol) by accepting HTTP requests from clients and then serving them usually a HTML (hypertext markup language) or XHTML document, although other file types are possible including images, documents, or other raw files. Most web servers also include logging, where sometimes detailed information about clients and client requests can be stored in log files, for later statistical analysis. The web server/computer distinction can be misunderstood by the public. A web server is either a computer program devoted to accepting HTTP requests, providing HTML/XHTML responses, and logging, or a computer that runs such a computer program. Web servers are one of the primary components of the Internet and of computer networking.

URLs and Networks

The Internet is the most pervasive and obvious example of a computer network, although more selective and private networks operate using web servers as well, like local area networks (LANs), which may in turn communicate with the world wide web. These networks use URLs to locate information, and you may know more URLs than you think. Every common web address is an example of a URL. When a network-connected computer user tries to access a URL, the browser on that computer connects to the server and requests content at that address. The URL is used to index the content on the web server, which delivers the content according to the request. This is the basic mechanism of requesting a web page on the Internet from your PC, although the specific detailed process is more complex.

Detailed Process: Protocol and IP Addresses

When a URL is typed into a browser, the first part of the URL represents the protocol (usually HTTP), followed by the server name (www.examplewebsite.com), followed by the file name, (/content.htm). This URL translates the server name into an IP address, which is then connected to a port. The server receives the "Get" request for the file "www.examplewebsite.com/content.htm" and sends the HTML text for the web page to the browser and any cookies associated with the content. The browser then reads the HTML and formats the page for your screen. By using web servers (meaning both programs and computers that run those programs), the greatest network in the history of civilization has been created, the Internet, all from the most meager of building blocks.

References

• The Complete Idiot's Guide to the Internet; Peter Kent; 7th Ed, 2001.
• Web Server Technology; Nancy J. Yeager; 1996.