A parked domain is one which is taken, yet it is not associated with another service - web or email hosting. Basically, this type of domain address will not open any real content if you type it inside an Internet browser, but nobody else can take it as you've already registered it and you are its owner. The main advantage of acquiring a domain name and parking it afterwards is that you will be able to keep it and not worry that someone else could possibly register it meanwhile if, for instance, the website for it is not ready yet. You could set a short-term Under Construction webpage for a parked domain address while you are working on the site, or forward it to another 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, so that you can protect a brand name or a trademark. In cases like this, the .net and .org domain addresses can be parked and directed to the .com since you do not need individual sites for them.