There are 2 services you'll need for a functioning web site - a domain name and a website hosting plan for it. Whenever you type the domain address in your web browser, you see the content that is uploaded in the web hosting account, but if that domain name is not linked to such an account or to an e-mail service, it is parked. In other words, the domain address 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” page from the registrar company, or it could be forwarded to any other URL of your choice. The main benefit of parking a domain name is that you can keep it and be sure that no one else is going to take it. In the meantime, it's not going to block a slot for a hosted domain address inside your account. In addition, you can park domains if you have a .com, for example, and you register domains with other extensions like .net, .org or country-code ones to forward them to the main website in order to protect a brand name.