History of Yahoo!
On March 8, 1997, Yahoo! acquired online communications company Four11. Four11's webmail service, Rocketmail, became Yahoo! Mail. Yahoo! also acquired ClassicGames.com and turned it into Yahoo! Games. Yahoo! then acquired direct marketing company Yoyodyne Entertainment, Inc. on October 12, 1998. In January 1999, Yahoo! acquired web hosting provider GeoCities. Another company Yahoo! took over was eGroups, which became Yahoo! Groups in June 2000. On March 8, 1998, Yahoo! launched Yahoo! Pager, an instant messaging service that was renamed Yahoo! Messenger a year later.
Windows Live Messenger
On October 13, 2005, Yahoo! and Microsoft announced plans to add interoperability between their messenger services. The announcement came after years of third-party interoperability success (most notably, PowWow by Tribal Voice, Trillian, Pidgin) and criticisms from Tribal Voice and iCast that the major real time communications services were locking their networks. Yahoo! and Windows Live Messenger became interoperable on July 12, 2006. For six years, Yahoo! Messenger and Windows Live Messenger users in possession of up-to-date software could communicate across the two networks. Instant messaging as well as transmission of emoticons, nudges, offline messages, presence information and personal status messages were supported. On December 14, 2012, the interoperability ended.