For those who are not in the know, expired domain names are fast becoming a powerful source for potential web traffic and profits. There are various tools online that can help you tap into the vast potential of domain names that have expired and are now available for you to buy a domain.What exactly are expired domain names? These are domains that used to be listed under another owner. However, the owners of these expired domains might have given up their domains due to various reasons - some common causes being a non-renewal of the domain after their registration contracts have expired either due to lack of funds or closure of the business.