This is the official version of the Yahoo! Instant Messenger. Although several programs have been released that allow you to use Yahoo!, this official version has a lot of features that the other clients do not have, such as integration with other Yahoo! services. In addition to instant messages, this client maintains your friend list. It is stored on the server, rather than on your hard drive. This is a huge benefit, since hard drives sometimes get formated! The program also allows you to maintain an ignore list, and it will even run invisibly, so you can check offline messages without being bothered. This client is suprisingly stable. It is a very well built program that I would suggest to anyone. If you Yahoo!, you need this program!