Google Talk (GTalk) is a free Windows and web-based application for instant messaging and voice over internet protocol (VOIP), offered by Google Inc. The first beta version of the program was released on August 24, 2005.

Instant messaging between the Google Talk servers and its clients uses an open protocol, XMPP, allowing users of other XMPP/Jabber clients to communicate with Google Talk users. VoIP in Google Talk uses an older version of what would later become the Jingle protocol. The technology used within the Google server network however is not publicly known.

The Google Talk client is only available for Microsoft Windows (2000, XP, Server 2003, Vista and Windows 7). Mobile clients are also available for the Palm Pre, BlackBerry, iPhone and Android-based devices. With the release of the Google Talk gadget, users of all platforms supported by Adobe Flash Player can also use Google Talk.^[1] Many other XMPP clients are compatible with Google Talk, and support a variety of other platforms.