There are two services you need for a functioning website - a domain plus a hosting plan for it. When you type the domain in your web browser, you see the content that is uploaded within the web hosting account, but if that domain address isn't linked to such an account or to an e-mail service, it's parked. Put simply, the domain name is registered and you're its owner, but it does not have any content of its own. Instead, 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 make certain that nobody else will take it. In the meantime, it will not block a slot for a hosted domain in your account. You may also park domains if you have a .com, for example, and you register domain addresses with other extensions like .net, .org or country-code ones to forward them to the main website as a way to protect a brand name.