A parked domain is one which is taken, but it's not associated with some other service - web or e-mail hosting. Put simply, this kind of domain name will not open any actual content when you type it within a web browser, but nobody else can take it as you've already registered it and you are its owner. The benefit of getting a domain name and parking it afterwards is the fact that you can keep it and not stress that somebody else may register it meanwhile if, for instance, the site for it is not ready yet. You can create a short-term Under Construction webpage for a parked domain address while you are working on the web site, or direct it to some other web address - temporarily or permanently. The second option can be used if you have already registered domain.com, for example, and you obtain domain.net and domain.org, so as to protect a brand name or a trademark. In such a case, the .net and .org domain names can be parked and directed to the .com since you don't need individual sites for them.