A subdomain is an easy way to create a memorable Web address for unique content areas of your site.
For example, you could create a subdomain for pictures on your site called "pics" that is accessible through the URL pics.example.com in addition to www.example.com/pics.
Do not use "localhost" as the host name for your database-driven websites. Once you have successfully created a database, your host name displays on the Database Information page of your Hosting Control Center .