Android 10 introduced full gesture navigation without the traditional navigation buttons.
Earlier Android versions experimented with gestures. Android 9.0 Pie introduced a two-button, pill-style system, but Android 10 replaced that approach with edge swipes and a gesture bar: swipe up for Home, swipe up and hold for Overview, and swipe from either edge for Back.
The change was not completely mandatory for users. Android 10 continued to support the classic three-button navigation system, and devices upgrading from Pie could retain the older two-button layout. Google’s compatibility requirements did, however, require new devices to support Android 10’s gesture system.
A common mix-up is treating any gesture-based navigation as Android 10’s feature. The more precise distinction is that Pie introduced the earlier two-button gesture interface, while Android 10 introduced the modern full-screen system with no persistent navigation buttons. Some manufacturers also added their own gesture schemes, but those were separate from Android’s standard implementation.