If you wish to register a domain to ensure that nobody else will take it, but you haven't developed the site for it yet, you could park it. That is a feature that registrar companies provide if a domain name is not connected to any web or email hosting service. By doing this, you are able to protect a brand name, for instance, and you will own the domain in question although it will not load any content. If you'd like, you may choose some standard template that the registrar provides, such as For Sale or Under Construction, or you can forward the domain name to a new web address. Your second option is very helpful in case you own a number of domain names, but you want all of them to open the same website. For instance, you could register domain.net and domain.org, then park them and forward them to domain.com. In this example, you're going to need hosting for the third domain only and the traffic to the other ones will be redirected to it.