A parked domain name is one that's taken, but it is not associated with some other service - web or email hosting. Put simply, this type of domain name won't open any actual content in case you type it inside a web browser, but nobody can take it as you have already registered it and you are its owner. The main advantage of obtaining a domain and parking it afterwards is that you will be able to keep it and not worry that somebody else could possibly register it meanwhile if, for instance, the site for it is not ready yet. You may set a temporary Under Construction website page for a parked domain name while you're 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 acquire domain.net and domain.org, in order to protect a brand name or a trademark. In cases like this, the .net and .org domains can be parked and directed to the .com because you don't need separate websites for them.