Sub Domains

Most people are unaware that they use sub domains daily. The famous "www" of the World Wide Web is an example of a sub domain. Sub domains can be created on a DNS server, and they don't need to be registered with a domain name registrar, of course, the original domain name needs to be registered before a sub domain could be created.
Examples of sub domains used on the internet are http://store.apple.com and http://support.microsoft.com.
Sub domains can be requested from your web hosting provider.