Windows Live Messenger

MSN Messenger (also known colloquially simply as "MSN"), later rebranded as Windows Live Messenger, was a cross-platform instant-messaging client developed by Microsoft. It connected to the now-discontinued Microsoft Messenger service and, in later versions, was compatible with Yahoo! Messenger and Facebook Messenger. The service was discontinued in 2013 and was replaced by Skype.

The client was first released as MSN Messenger Service on July 22, 1999, and was marketed under the MSN brand until 2005, when it was rebranded under the Windows Live name. It has since been officially known by the latter name, although its first name remained in common use. In June 2009, Microsoft reported the service attracted over 330 million active users each month, placing it among the most widely used instant-messaging clients in the world.

Following its acquisition of Skype Technologies in May 2011, Microsoft added interoperability between Skype and Microsoft accounts, allowing Skype—which had features unique to its platform and a wider user base—to communicate with Windows Live Messenger contacts. In 2013, the product was discontinued, and Microsoft began cutting service to existing clients. It remained active in China for another 18 months and ceased operations there on October 31, 2014.