'What is Google Duo?': Everything you need to know about Google's cross-platform video chat app, including how to use it

Google/YouTube

Google Duo is a simple video-chatting service that can connect between iPhones and Android phones.

• Google Duo is a simple video chat app published by Google.
• There are versions available for both iPhone and Android, so you can chat regardless of what kind of phone the other party has.
• Duo's "Knock Knock" feature lets you see live video of the caller before you accept the call.
• Visit Business Insider's homepage for more stories.

Google Duo is a simple video chat app that works on both iPhone and Android devices. Introduced by Google in 2016, it is one of several chat and video apps offered by the search company.

Duo is unique from other past and present Google video and chat apps (like Hangouts and the now-shuttered Allo) in that it is designed to be a fast and easy one-to-one video chat app like Apple's FaceTime. But because it's cross-platform, Android and iPhone users can video chat with one another.

Dave Johnson/Business Insider

It might not be apparent, but this is a Google Duo video call between an iPhone and Android.

What you can do with Google Duo

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 contact list. If you want to call someone who isn't a Duo user, Duo knows that and offers to send a text message inviting them to install the app.

The app has a number of other convenient features as well. It automatically switches between your cellular network and Wi-Fi, for example, and takes advantage of Wi-Fi to work in 720p high definition, when possible. And if the person you are calling doesn't answer, you can leave a video message for them. You can also record short pre-recorded messages to send to select contacts, and you can choose to make audio-only calls as well.

Perhaps the most notable feature that Duo offers, though, is called "Knock Knock." Knock Knock lets the recipient of a call see a live preview of the caller before needing to accept the call - so you can see who is calling you, what they look like, and even where they are before you choose to answer. Google also provides the ability to turn off Knock Knock if you prefer not to use it.

Recently, Google has updated Duo to support group calls with up to four people. This hasn't been released worldwide, but in the US, the app now features group calling.

For most users, you need to install Google Duo to begin using it. You can install Google Duo for the iPhone or Google Duo for Android. Some Android models, though, such as Pixel, Nexus, and Android One phones, now come with Duo preinstalled like FaceTime on iPhones.

How to use Google Duo

Google Duo is a very simple app to use. After installing the app, follow the setup instructions by entering your phone number and then entering the confirmation code that is texted to you. Then you can make a call.

1. Start the Google Duo app.

2. By default, you make a video call. If you prefer to make a voice-only call, tap the phone icon.

3. Tap "Search contacts or dial number."

4. Tap the name of the person in your contacts whom you want to call. If the person isn't in your contacts, enter their phone number instead.

Dave Johnson/Business Insider

Duo lets you choose a contact to call from your contacts list, or by entering a phone number manually.

5. If your contact already uses Duo, the number will dial. If not, Duo will offer to send a text message inviting them to install Duo.

You can also make a group call. To do that, tap "Create Group" and tap up to three people and tap "Done." Then tap "Start" to make the call.

Get the latest Google stock price here.