So, what is an agent? It is just a software program that is designed to do some job for you. In this context we are talking about software programs that interact with the Web. They can be simple or very complex. They may be tightly controlled, having to report back to you before taking any action, such as purchasing something. Or, they may be quite autonomous, such as an agent you have authorized to search for the best price and buy you the latest Garth Brooks CD.