Multiple sign-on, which enables you to be logged in to more than one Google Account at a time, will be enabled across many of Google’s products. This means that while logged in to your personal Gmail, you can also log in to your professional Gmail account without signing out of the other.
The company warned that not all products support multiple sign-on at this time. If you try to access a Google product that doesn’t support Account Chooser, you’ll be automatically switched to your default account (the one you were logged in to when you enabled the feature).
If you no longer wish to use Account Chooser, you can disable it (look for the option in the page’s footer) and turn it back on at any time. With Gmail becoming more interactive, the ability to seamlessly switch between accounts will become more convenient. If you enable this feature, be sure that you’re sending emails from the intended account, and don’t forget about account safety and privacy tips.