A parked domain address is one which is taken, however it's not connected to some other service - web or e-mail hosting. To put it differently, such a domain will not load any actual content when you type it inside a browser, but nobody else can take it as you have already registered it and you are its owner. The benefit of getting a domain name 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 site for it is not ready yet. You can set a short-term Under Construction page for a parked domain name while you're working on your web site, or forward it to another web address - temporarily or permanently. The second option can be employed when you have already registered domain.com, for example, and you acquire domain.net and domain.org, in order to protect a brand name or a trademark. In this case, the .net and .org domains can be parked and forwarded to the .com since you do not need individual websites for them.