Subdomains are sort of a site within a site. They are not, however, simply additional pages of an existing web site. The subdomain can have a web site all its own, completely separate from the site located at the main domain name.

To understand the use and purpose of subdomains, it may be necessary to first understand the concept of an internet domain name. Every web site that is active on the internet (and there are literally billions of them now - it was estimated as long ago as 1996 that there were more web pages in existence than there were people on Earth) has a unique domain name. There can be only one Ebay dot com, for example, on the entire internet. The domain name, however, is really just a way for humans to relate to the site. Internet servers see web site names as unique I.P. addresses. It is the domain name server that translates those numbers into names and back again.

A subdomain is simply an offshoot of your web site's domain. In terms of the way it appears on the server, the subdomain is simply a folder or a sub directory located within your domain's root directory. Any sub directory can serve as a sub domain. For example, if your web site is "www.mycompany.com" and you store the images for your site in a directory called "images," then you could, if you wished, create a subdomain at "images.mycompany.com". As long as you put an "index.html" page in the folder you should be able to pull it up in a web browser that way. In most cases you will create a new sub directory to be associated with a subdomain and some web hosts do not support subdomains on their servers or put a limit on the number of subdomains you may associate with your site.

The benefits of using subdomains as opposed to opening multiple hosting accounts are twofold. First, you get the obvious benefit of only having to pay for one hosting account. You also benefit from being able to have a completely separate web site, but one that your customers will easily recognize as being associated in some way with your business. Some companies will set up subdomains for various divisions (xyz.com may also have sales.xyz.com or support.xyz.com) and some will use subdomains for various businesses that are all offshoots of the same parent company.

That association could be a downside to using subdomains as well. If you want to keep the relationship between your companies under wraps (like Disney tried so hard to do with Touchstone Pictures so many years ago), you may want to use multiple accounts rather than subdomains. The web address clandestineproducts.megamall.com would clearly betray that there was some connection between Clandestine Products and Megamall, whether you wanted that information to be known or not.

About the author:
John Michaels is a freelance author for WebHostPacks.com where he regularly publishes articles on how to find a cheap web host and reviews of low cost web hosting services.