Hangouts give you multi-way Google Talk chat features plus multi-way voice and video meetings with screen sharing, all with encrypted true-to-life video and high fidelity audio. Connect with multiple people around the world at the same time.

Hangouts are limited to 10 video conference participants, with no time limit. You can also use Hangouts On Air to broadcast a hangout to many more people, though there is still a limit of 10 active participants.

If you activate Google+ premium features, the limit increases to 15 participants for both Hangouts and Hangouts On Air.

When users start a hangout, they can invite individuals, one or more of their circles, or a combination of both. That can include people outside of your domain or organization, but you can restrict access to hangouts by default.

All hangout video and audio streams are encrypted, so when users are off site, they can still join hangouts securely from outside of your company without VPN. In addition, all other features of hangouts (such as chat and integrated Google Drive files) are served over https, with the exception of YouTube content.

No. Information shared during the hangout, such as Google Drive files, group chats, and screenshares, is not stored during or after the hangout by Google Hangouts or Google+.

Google+ Hangouts run through Google's network in order to provide the best user experience and integrate with Google Drive files, Chat, and other Google products.

Yes, but it will also disable all video chats, including those started from Gmail. Hangouts respect the video chat setting in the Admin console.

To disable all hangouts and video chats:

1. Sign in to the Google Admin console. 
2. Do one of the following:
   • In the classic Admin console, click Settings > Talk.
   • In the new Admin console, click Google Apps > Talk.
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3. Select the organization where you want to disable video chats.
4. In the Additional Services section, uncheck Allow users to place video calls from chat to other chat users.

They will need to have the Google video chat plug-in installed. You can get it here. This is required to place a video call from Google Talk or Gmail, or to enter a hangout. Each user will be prompted to install this plug-in when first joining or starting a hangout, if they don't already have it.

Yes, we now have an MSI installer for Windows environments. Otherwise users are prompted to install the plug-in when joining or starting a hangout, if they don't already have it.

See System requirements.

If you decide to disable Google+, you can still keep the plug-in for Google Talk text, voice, and video chats. (The Google Talk service is also known as Chat.)

If you also don't use Google Talk and you want to uninstall the video plug-in, follow the steps below.

To uninstall in Windows:

1. Access the Windows Program Manager:
   • For Windows XP, click Start > Settings > Control Panel > Add or Remove Programs.
   • For Windows Vista, click Start > Settings > Programs and Features.
   • For Windows 7, click Start > Control Panel > Programs and Features.
2. Scroll down and select the Google Talk plug-in.
3. Click Remove or Uninstall.

To uninstall in Mac OS X:

1. In Finder, navigate to Applications > Utilities.
2. Open the Terminal application.
3. Copy and paste the following command into the window:

   ./Library/Application Support/Google/GoogleVoiceAndVideoUninstaller.app

4. Press Enter on your keyboard.