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.

Yahoo Messenger was originally launched under the name Yahoo Pager on March 9, 1998.

In addition to instant messaging features similar to those offered by ICQ, it also offers (on Microsoft Windows) features such as: IMVironments (customizing the look of Instant Message windows, some of which include authorized themes of famous cartoons such as Garfield or Dilbert), address-book integration and Custom Status Messages. It was also the first major IM client to feature BUZZing and music-status. Another recently added feature is customized avatars. Yahoo Messenger also allows users to access Yahoo Chat Rooms. As of December 14, 2012, all public chat rooms on Yahoo Messenger have been shut down as part of a series of features being changed/added/deleted.