Discontinued (June, 2017) instant messaging and VoIP service built on open standards provided by Google that could be accessed through Gmail. Also known as Google Chat.

Using the Extensible Messaging and Presence Protocol (XMPP), Google Talk was an instant messaging and voice over IP application that allows users with a Google account to text and video chat from within their browser.

The web app was called . It could be found in if users have set the old chat instead of . However, as of June 26, 2017, the chat in Gmail has also been turned off.

It used to have a Windows client but it was deprecated on 2015.

From Goodbye to the Google Talk app for Windows - Talk Help

The Google Talk app for Windows was shut down on February 23, 2015. If you try to use the Google Talk app, you'll see a sign-in error, and we'll send you an email explaining what's happened.