There are two services that you’ll need for a working site - a domain plus a web hosting plan for it. If you type the domain in your web browser, you see the content that’s uploaded in the web hosting account, but if that domain name isn't linked to such an account or to an e-mail service, it's parked. To put it differently, the domain name is registered and you are its owner, but it doesn't have any 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 could be forwarded to any other URL of your choice. The main advantage of parking a domain is that you can keep it and be sure that nobody else is going to take it. Meanwhile, it won't block a slot for a hosted domain address within your account. You could also park domains if you have a .com, for example, and you register domain addresses with other extensions such as .net, .org or country-code ones to forward them to the main web site as a way to protect a brand name.