There are two services that you need for a working website - a domain plus a hosting plan for it. Each time you type the domain in your web browser, you see the content that is uploaded in the web hosting account, but if that domain name isn't linked to such an account or to an email service, it's parked. To put it differently, the domain address is registered and you are its owner, but it lacks content of its own. As a substitute, 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 main benefit of parking a domain address is that you can keep it and be sure that nobody else is going to take it. Meanwhile, it will not occupy a slot for a hosted domain address inside your account. You can also park domains if you have a .com, for instance, and you register domains with other extensions such as .net, .org or country-code ones to forward them to the main web site in order to protect a brand name.