If you'd like to register a domain to ensure that no one else is going to take it, however, you have not built the site for it yet, you can park it. It's a service that registrar companies provide if a domain is not connected to any web or email hosting service. This way, you'll be able to protect a brand name, for instance, and you will own the domain name in question although it won't open any content. If you would like, you can choose some standard template that the registrar provides, like For Sale or Under Construction, or you can forward the domain to a different web address. Your second option is very useful if you own a number of domains, but you want every one of them to open the same site. As an illustration, you can register domain.net and domain.org, then park them and forward them to domain.com. In this example, you will need hosting for the third domain only and the traffic to the other ones will be redirected to it.