Google Talk, also known as GTalk, is a Windows and web-based application for voice over internet (VOIP) and instant messaging, offered by Google Inc. It was released on August 24, 2005. It uses an open protocol, XMPP, allowing users of other XMPP clients to communicate with Google Talk users. VoIP in Google Talk is based around the Jingle protocol. Many other XMPP clients are compatible with Google Talk, and support a variety of other platforms.
MSN Messenger is a freeware instant messaging client.it currently ranks 2 after AIM/ICQ. It was developed by Microsoft in July 1999. It was renamed Windows Live Messenger in February 2006 as part of Microsoft's Windows Live series of online services and software. MSN Messenger is often used to refer to the .NET Messenger Service (the protocols and server that allow the system to operate) rather than any particular client.