The hosted domains feature of a hosting account denotes the number of registered domains that one could include in the very same account. Registering a domain name and hosting it are 2 different services although a lot of people consider them to be the same thing. While the registration means you become the owner of a certain domain, the hosting aspect is what really allows you to have a site since this is where your files and email messages are going to be. Because these are 2 independent services, it is possible to register a new domain with one company and host it with another one by modifying its name servers (DNS) - the domain address shall work in the exact same way just as if it was registered and hosted with the same company. It's also extremely important to know that changing the hosting means pointing the domain to a different company and not transferring it.