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.
Yahoo! Messenger
Interoperability between Yahoo and Windows Live Messenger was launched July 12, 2006. This allowed Yahoo and Windows Live Messenger users to chat to each other without the need to create an account on the other service, provided both contacts used the latest versions of the clients. It was not possible to talk using the voice service between the two different messengers.