A parked domain name is one that is taken, but it is not associated with some other service - web or e-mail hosting. In other words, such a domain will not load any real content when you type it in a browser, but no one else can take it as you've already registered it and you are its owner. The advantage of getting a domain and parking it afterwards is that you can keep it and not worry that somebody else could possibly register it in the meantime if, for instance, the site for it is not ready yet. You could create a short-term Under Construction website page for a parked domain while you're working on the website, or forward 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 acquire domain.net and domain.org, so as to protect a brand name or a trademark. In cases like this, the .net and .org domains can be parked and forwarded to the .com because you do not need separate sites for them.