Yahoo!
Yahoo grew rapidly throughout the 1990s. Yahoo went public in April 1996 and its stock price rose by 600 percent within two years. Like many search engines and web directories, Yahoo added a web portal, putting it in competition with services like Excite, Lycos and America Online. By 1998, Yahoo was the most popular starting point for web users, and the human-edited Yahoo Directory the most popular search engine, receiving 95 million page views per day which was triple the number compared to rival Excite. It also made many high-profile acquisitions. Yahoo began offering free e-mail from October 1997 after the acquisition of RocketMail, which was then renamed to Yahoo! Mail. In 1998, Yahoo! decided to replace AltaVista as the crawler-based search engine underlying the Directory with Inktomi. Yahoo's two biggest acquisitions were made in 1999 - that of Geocities for $3.6 billion, and Broadcast.com for $5.7 billion.
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.