Google Sign-In is a library that helps you implementing authentication/authorization using Google accounts to your app. In this video, we'll walk you through the concept of Google Sign-In and show you how to implement authentication on server less apps. Google Sign-In for Websites: https://goo.gl/5MiKLZ Google Developer Console: https://goo.gl/ppwHMi Design Guidelines: https://goo.gl/BrLYKy Googl