Although Duo is available on both iOS and Android, Google's goal is clearly to give Android users a FaceTime-like experience...Google had three priorities when it crafted what it sees as the perfect app for one-to-one videoconferencing: simplicity, speed and "human" features.

The simplicity is apparent as soon as you launch the app. Similar to Snapchat, you're greeted with a view from your phone's camera, although on Duo it's your selfie cam...there's a row of yellow circles that show your most recent calls. In the bottom left is the big, blue call button; tapping it brings up a list of your phone's contacts.

...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...