Google's oft-rumored new messaging service is real, and it's called Hangouts. Google just officially introduced Hangouts during its I/O keynote, announcing that the service will be available today on Android, iOS and the web. You can see the app's green icon on the Android home screen up above.

Upon opening the Hangouts app, a user will be presented with a list of his or her ongoing conversations. Hangouts chat histories will be saved by Google, and any images that are shared during a conversation will be saved to an album. Just like other messaging services, Google Hangouts will support chats with both single users and groups, and users will also be able to take part in group video chats. Another Hangouts feature that Google touted is synced notifications, which will ensure that users won't need to clear out their Hangouts alerts when hopping between devices.

As I mentioned previously, Hangouts will be available on Android, iOS and the web. Mobile users will be able to download the app later today from the Google Play Store and Apple App Store, while Chrome users will be able to grab Hangouts from the Chrome Web Store. Google says that Hangouts will also be available in Gmail and Google+. We'll be sure to update you when the app goes live in the various app stores. Until then, you can check out a brief Hangouts promo video at the bottom of this post.

UPDATE: The Hangouts apps for Android, Chrome and iOS are now live. It's worth noting that the Android app is an update to Google Talk app that replaces the old app. Here are the links to all three app stores:

• Hangouts on Google Play
• Hangouts on Chrome Web Store
• Hangouts on App Store