What is domain & subdomain?

Domain names are simply addresses to websites. For example www.stanford.edu is a domain name.

A subdomain is a way to organize and separate content on your website. For instance, sub.mydomain.com is a subdomain of mydomain.com.

If you possess a domain, you are able to create an almost infinite number of subdomains (or directories such as sub.mydomain.com/directory) associated with it. In practice, this allows a user to simultaneously install multiple web applications to each of their subdomains or directories (such as WordPress, Omeka, MediaWiki, and/or Drupal).

For more information please refer to the support article on subdomains.