A parked domain is one which is taken, however it's not linked to some other service - web or email hosting. Essentially, this kind of domain will not load any actual content when you type it inside a web browser, but no one else can take it as you have already registered it and you are its owner. The advantage of getting a domain and parking it afterwards is that you’re able to keep it and not stress that somebody else might register it meanwhile if, for example, the website for it is not ready yet. You can create a temporary Under Construction website page for a parked domain while you're working on the website, or direct it to another web address - temporarily or permanently. The second option can be used when you have already registered domain.com, for instance, and you obtain domain.net and domain.org, so that you can protect a brand name or a trademark. In this situation, the .net and .org domains can be parked and forwarded to the .com because you do not need different sites for them.