Google is expanding its Google+ social network by launching Google+ Sign-In, a new feature that allows users to log-in to Android, iOS, and web apps through Google+, instead of creating a new account.\u00a0Facebook Connect and Twitter offer a similar feature, doing away with the need for having\u00a0to remember a new username and password.Google says developers can take advantage of the feature with their Android, iOS or web app. For users, Google says it is a simple and secure way to log-in and "prohibits social spam".To get started, users simply log-in with their Google username and password and are presented with what the app wants to access from the account (profile information, Gmail, and more) - similar to the feature users are presented with when downloading an app from Google Play.\u00a0Another feature Google+ Sign-In offers is when a user signs into a service's web app, its mobile app can be installed on their Android device with a single click.Lastly, in typical Google fashion, Google+ Sign-In enables social sharing, including game scores and app accomplishments (as with\u00a0a fitness app). When you share from an app that uses Google+ Sign-In, it will be posted as a new "interactive" post in the Google+ stream. Clicking on the link launches the app from which\u00a0it was shared.Google+ Sign-In is now available for developers to begin integrating into their applications. Among the first applications to feature it include Fitbit, Flixster, The\u00a0Guardian and USA Today.