If you want to register a domain name to make sure that nobody else will take it, but you have not developed the site for it yet, you can park it. This is a feature that registrar companies offer if a domain address isn't connected to any web or e mail hosting service. By doing this, you can protect a brand name, for example, and you will own the domain address in question even though it will not open any content. If you want, you can pick some standard template that the registrar provides, like For Sale or Under Construction, or you can direct the domain to an alternative web address. Your second option is extremely helpful in case you own a few domains, but you want each and every one of them to open the same website. For instance, you can 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 only and the traffic to the other ones is going to be redirected to it.