Winows Live Messenger is an instant messaging client for Windows XP, Windows Server 2003, Windows Vista, and Windows Mobile, first released on December 13, 2005 by Microsoft. It is the successor to MSN Messenger. It is part of Microsoft's Windows Live set of online services. The current stable version is Windows Live Messenger 2008 (a.k.a. version 8.5), which was released on November 6, 2007.