There are two separate services you need for a functioning website - a domain plus a website hosting plan for it. Any 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 name is not 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 does not 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 main benefit of parking a domain address is that you can keep it and be sure that no one else will take it. At the same time, it's not going to take a slot for a hosted domain name inside your account. You may 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 in order to protect a brand name.