When users sign in with Google, they can now choose to bring their Google+ info with them (like their public profile, and the people in their circles). This lets your app welcome users by name, display their picture, connect them with friends, and lots more. A messaging app gets better with your best friends, just like a cooking app is more welcoming when it knows your name.
Create accurate profiles
Profiles on your site are more engaging and relevant for users if you already know a bit about them. You can generate profiles in your app without users needing to start from scratch or maintain a separate profile just for your app.
Help users find other friends who use your service through their Circle connections on Google+. For instance, you can recommend people to follow in your app or help users recommend your app to their friends based on who they are connected to on Google+. By connecting friends and colleagues, you can build lasting relationships and grow user networks in your app.
Spark content discovery
Maximize social engagement with just the right content. With user's permission, you can customize your app with information like the user's name, age range, and locale. You can make your app experience more personal and engaging by showing relevant content based on a user's recent public activity on Google+. Help users discover great things their friends have shared, reviewed, purchased or added to a wishlist. For instance, you can surface reviews created by a user's friends to showcase the most relevant product feedback.
Create dynamic marketing campaigns
Segment customers and identify influencers based on public information from your users’ profiles. This lets you tailor special offers and customize promotional content based on locale, age range, or size of their network. In addition, you can request users’ permission to communicate with them by email.