Details:
Subdomains are additional domain names that enable you to:
>Organize logically the structure of your site
>Host additional Web sites or parts of a Web site on the same server without the
need to pay for registration of additional domain names
An example of using subdomains: You have a Web site your-product.com
dedicated to promoting your software product. For publishing user's guides,
tutorials and list of frequently asked questions, you can organize the
subdomain 'userdocs' so that your users will be able to access online user
documentation directly by visiting the domain name userdocs.your-product.com.