Google Hangouts is an instant messaging and video call service that is embedded in multiple Google web services and can be use as a web and mobile standalone app.
Google Hangouts was originally launched as a service embedded into Google+. Nowadays it could be accessed in several ways
- http://contacts.google.com (Preview)
- Chrome Extension for Google Hangouts.
- Chrome Desktop App for Google Hangouts
- Android app.
- iOS app.
It could be used to chat through instant messaging with users of Google Chat and third party chat clients and to have video calls with multiple participants. Video calls also could be enhanced by adding real time interaction apps.
Hangouts on Air while originally was promoted by Google as the same app, its documentation is kept as part of the Classic Google+ Help Center, still has its landing page inside of the old Google+ and due to its integration with Youtube, it should be considered as another web app.