Duo uses your phone's contact list -- not your Gmail contacts. And when you first set up the app, you do so with your phone number and not your Google account. This is a big deal, but more on that ...

Thanks to some smart (and aggressive) marketing, Duolingo has cemented itself as one of the most popular language learning apps in the world. That said, it isn't without competition: There are plenty ...

Users don't need to log into their Google account or create any new usernames or passwords to use the Google Duo app. Duo is based on phone numbers, so you can call people from your phone's ...

or Google Play (Android). Click "Next" after you have the Duo Mobile App installed on your device. 7. Once you have installed the Duo app on your smartphone, open the app and activate it by following ...