A parked domain name is one that's taken, however it's not connected to some other service - web or email hosting. Basically, this kind of domain address won't open any real content when you type it in a web browser, but nobody can take it as you have already registered it and you are its owner. The benefit of obtaining a domain and parking it afterwards is the fact that you are 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 set a temporary Under Construction webpage for a parked domain name while you're working on your web site, or direct it to another web address - temporarily or permanently. The second option can be employed if you have already registered domain.com, for instance, and you get domain.net and domain.org, so that you can protect a brand name or a trademark. In this situation, the .net and .org domain addresses can be parked and forwarded to the .com since you do not need different sites for them.