There are 2 services you'll need for a functioning site - a domain and a website hosting plan for it. Each time you type the domain address in your browser, you see the content that is uploaded inside the web hosting account, but if that domain is not linked to such an account or to an email service, it's parked. To put it differently, the domain is registered and you are its owner, but it doesn't have any content of its own. Rather, it can open either a pre-made “Under Construction / For Sale” page from the registrar company, or it can be forwarded to any other URL of your choice. The benefit of parking a domain address is that you can keep it and make sure that nobody else is going to take it. At the same time, it's not going to block a slot for a hosted domain address within your account. You may also park domain names if you have a .com, for example, and you register domain addresses with other extensions such as .net, .org or country-code ones to direct them to the main web site so as to protect a brand name.