A parked domain address is one that is taken, yet it is not associated with some other service - web or e-mail hosting. Put simply, this type of domain name will not open any real content if you type it in a browser, but nobody can take it as you've already registered it and you are its owner. The advantage of acquiring a domain and parking it afterwards is the fact that you are able to keep it and not stress that somebody else may register it meanwhile if, for instance, the website for it is not ready yet. You may create a temporary Under Construction website page for a parked domain while you are working on the website, or direct it to some other web address - temporarily or permanently. The second option can be used when you have already registered domain.com, for instance, and you get domain.net and domain.org, in order to protect a brand name or a trademark. In such a case, the .net and .org domain addresses can be parked and directed to the .com because you do not need different sites for them.