Windows Live Messenger (WLM), formerly and still commonly referred to as MSN Messenger or MSN, is a freeware instant messaging client for Windows XP, Windows Server 2003, Windows Vista, and Windows Mobile, first released on July 22, 1999 by Microsoft. It is the world’s largest easy-to-use consumer instant messaging service that allows people to connect with others in real time, expressing themselves in a rich, convenient and fun way.