There are two services you need for a working web site - a domain name and a hosting plan for it. If you type the domain name in your web browser, you see the content that’s uploaded within the hosting account, but if that domain address isn't linked to such an account or to an e-mail service, it's parked. To put it differently, the domain is registered and you're its owner, but it doesn't have any content of its own. Rather, it can open either a pre-made “Under Construction / For Sale” webpage from the registrar company, or it can be forwarded to some other URL of your choice. The benefit of parking a domain name is that you can keep it and ensure that nobody else is going to take it. At the same time, it won't block a slot for a hosted domain in your account. You may also park domain names if you have a .com, for example, and you register domains with other extensions like .net, .org or country-code ones to direct them to the main web site in order to protect a brand name.