Hangouts, previously Google Talk, is a free Windows and web-based application for instant messaging and voice over internet protocol (VOIP). It lets you send instant messages, do automatic file transfers, check friends' status updates, make PC-to-PC calls, and make conference calls to multiple people at once.
"Hangouts" are places used to facilitate group video chat (with a maximum of 10 people participating in a single Hangout at any point in time).
Within the 10 person limit participants may use voice only phones to dial in to the hangout instead of the desktop or mobile video chat feature.
On a desktop or laptop environment hangouts also contain the integration of group chat, Google document sharing, and synchronous viewing of YouTube videos.