Soon after Apple got rid of its home button and replaced it with gesture-based navigation, Android followed suit. But different OEMs had different interpretations for this navigation type. Google is looking to change that with Android Q. Gesture navigation will be the default with this version of Android, and it'll standardize the gesture system so it'll be easier to pick up. The beta version of the operating system has a new gesture system that gets rid of the back button. In its place, you swipe from the side of the screen. And the main gestures are similar to Apple's implementation.
The upside of gesture navigation is it does things like add function while using less screen real estate and make it easier to switch between apps. But if you're not into using gestures, you can still switch back to the three-button navigation.
Source: Phandroid