If you wish to register a domain to make certain that no one else is going to take it, however, you have not built the site for it yet, you may park it. This is a feature that registrar companies provide whenever a domain name is not linked to any web or email hosting service. That way, you'll be able to protect a brand name, for instance, and you'll own the domain name in question although it will not open any content. If you want, you can pick some default template that the registrar offers, like For Sale or Under Construction, or you can direct the domain to another web address. The second option is very helpful in case you own a few domains, but you want every one of them to open the same website. For instance, you may register domain.net and domain.org, then park them and forward them to domain.com. In this example, you are going to need hosting for the third domain address only and the traffic to the other ones will be redirected to it.