Sign-in with Google +

Google+ Sign-in provides the OAuth 2.0 authentication mechanism along with additional access to Google desktop and mobile features.

• https://developers.google.com/+/ provides the OAuth 2.0 authentication mechanism along with additional access to Google desktop and mobile features.
• Direct access to an authentication service based on the standardized OpenID Connect mechanism is also available. https://developers.google.com/accounts/docs/OAuth2Login