There are 2 services you need for a functioning website - a domain name plus a hosting plan for it. Any time you type the domain address in your web browser, you see the content that’s uploaded in the website hosting account, but if that domain 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 are 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 some other URL of your choice. The main advantage of parking a domain is that you can keep it and ensure that nobody else will take it. Meanwhile, it's not going to take a slot for a hosted domain inside your account. You could also park domain names if you have a .com, for instance, and you register domain addresses with other extensions like .net, .org or country-code ones to forward them to the main site so as to protect a brand name.