A domain is your website's address. For example, this website is Millennium Multimedia - the site consists of all the documents, text, graphics and images bound together. The domain, however, is e-2m.com. (I also own millenniummultimedia.com - you can have more than one domain pointing to a website.) You'll need to register a domain by purchasing it in yearly increments. As long as you keep paying the renewal fee, the domain is yours.