Google announced plans to completely shut down the Google Talk service after June 26, 2017. Users will be automatically transitioned to Google Hangouts, unless contractual commitments apply. Google started phasing out Google Talk in 2015 and recommended users to move to its new Hangouts service. Google Talk was launched in 2005, one year after Google launched Gmail, and was available as a desktop client and mobile app, but also as a web-based service embedded in the Gmail inbox. Google’s main goal was to make it possible every user on the Internet talk with his friends, regardless of his IM provider.
Source: https://www.bleepingcomputer.com/news/google/google-talk-to-be-shut-down-on-june-26/