Duo the google's new video chat application.

Google's new app, Duo, is a simple video-calling service that's available for Android and iOS today. Alongside the upcoming messaging app Allo, it's one of two communication apps Google announced earlier this year at its I/O conference, and one of four altogether from the company.

In a way, it's Google's answer to Apple's FaceTime, and it makes one-to-one calling between Android phones, and from Android to iPhone, very simple. Though both parties have to download the app to begin chatting (unlike FaceTime, which is baked into the dialer of compatible iPhones), it's still an intuitive app to use.