How We Can Sign in to other sites using Google

You may see "Google+ Sign-In" on third party websites, mobile apps, games, or other online services (generally referred to as “apps”). When you do, you can use your Google username and password to sign in, instead of creating a new username and password. And don't worry, you can control what information is shared with the site and what information others see.

If you haven’t connected any apps to Google+, that means you haven't signed in to any apps using Google+ Sign-In. That might include things like games, music, or social media sites.

Tip: If you’re having trouble signing in using your Google username and password, try this troubleshooter.

Getting started

When you sign in to a website or app with Google, you’ll choose things like:
 

• Who from your circles can see your app activity on Google-provided services like your Google+ profile, some Google search results, ads managed by Google (depending on your existing Google account settings).

• The list of people in your circles you share with the app.

 To use Google+ Sign-In, follow these steps:

1. Open the app or website you want to sign into.
2. Click the Google+ Sign-In button. If you don’t see the button, that may mean Google+ Sign-In isn’t available for the app, or you might already be logged in to the app.
3. If you aren’t already logged in to Google+, enter your Google username and password.
4. Review the permissions screen. From this screen, you can do things like:

• Choose who from your circles can see your app activity on Google-provided services
• Select the people or circles you want to share with the app
• Give the app access to other information it requests 

      5. Click Accept.

Once you’ve signed in with Google, the site or app may ask you to complete a few more steps to create your account.

Share your app activity with people you choose

Some apps may ask to share your app activity with Google. You choose who can see this activity on Google-provided services.

That means you might let everyone see the music you’re listening to, but only let your family see your restaurant reviews.

The app will show you a permissions screen if it would like to share your information on Google-provided services. To make changes, click the pencil icon on the permissions screen . After clicking the pencil icon, you can:

• Make your app activity visible by clicking +Add more people and entering circles, people, or email addresses.
• Remove a circle or person by clicking the X next to their name.
• Keep your activity private by selecting Only you.

Select the people you want to share with the app

When you share a list of people from your circles with the app, it may use that information to personalize your app experience. For example, you may see when your friend earns a high score on a game you both play, or when they use the app to review a restaurant you’re considering for dinner.

From the permissions screen:

1. Click the pencil icon. 
2. Uncheck the box next to any circles you’d like to exclude. You can also uncheck “All circles” and future circles you create won’t be automatically shared with the app.
3. Click OK.

 Sourced from Google help desk