There are two separate services you need for a working site - a domain and a hosting plan for it. If you type the domain name in your Internet browser, you see the content that is uploaded in the website hosting account, but if that domain is not linked to such an account or to an email service, it is parked. To put it differently, the domain name is registered and you are its owner, but it lacks content of its own. As a substitute, it can open either a pre-made “Under Construction / For Sale” webpage from the registrar company, or it may be directed to any other URL of your choice. The main advantage of parking a domain is that you can keep it and ensure that no one else is going to take it. In the meantime, it won't occupy a slot for a hosted domain address within 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 in order to protect a brand name.