The hosted domains feature of a web hosting account denotes the amount of registered domains that one can add within the same account. Registering a domain and hosting it are two totally different services although a lot of people consider them to be the very same thing. While the registration means that you become the owner of a given domain name, the hosting part is what really enables you to have a site because this is where your data and emails are going to be. Because these are two independent services, you are able to register a new domain address with one company and host it with another one by modifying its name servers (DNS) - the domain shall work in the exact same way just as if it was registered and hosted with the exact same company. It's also very important to know that changing the hosting means directing the domain name to an alternative company and not transferring it.