Yahoo! Messenger

Yahoo! Messenger (sometimes abbreviated YM) is an advertisement-supported instant messaging client and associated protocol provided by Yahoo. Yahoo Messenger is provided free of charge and can be downloaded and used with a generic "Yahoo ID" which also allows access to other Yahoo services, such as Yahoo Mail, where users can be automatically notified when they receive new email. Yahoo also offers PC-PC, PC-Phone and Phone-to-PC service, file transfers, webcam hosting, text messaging service, and chat rooms in various categories.