The hosted domains feature of a web hosting account indicates the amount of registered domain names that one can add within the same account. Registering a domain address and hosting it are two completely different services although many people consider them to be the same thing. While the registration means that you become the owner of a given domain address, the hosting element is what in fact enables you to have a website considering that this is where your files and e-mails will be. Because these are 2 separate services, you can register a new domain address with one company and host it with another one by modifying its name servers (DNS) - the domain name is going to work in the exact same way just as if it was registered and hosted using the same company. It's also very important to know that changing the hosting means pointing the domain name to another company and not transferring it.