Which Android version introduced Google's Material Design interface?

Android Lollipop introduced Google’s Material Design interface. Announced as Android L at Google I/O on June 25, 2014, Android 5.0 Lollipop brought a major visual redesign to the operating system. Google described Material Design as a responsive design language built around surfaces, depth, lighting, animation, and clear motion cues.

Material Design was intended to create a more consistent experience across Android phones, tablets, wearables, web services, and other Google products. The interface used card-like layouts, stronger shadows, grid-based spacing, animated transitions, and ripple effects when users touched buttons or controls.

Lollipop also introduced important technical changes, including Android Runtime (ART) replacing Dalvik, improved notifications on the lock screen, support for 64-bit processors, and Project Volta battery optimizations. The first phone to ship with Lollipop was the Nexus 6.

Marshmallow, Nougat, and KitKat are different Android releases. KitKat preceded Lollipop, while Marshmallow and Nougat followed it; none of those versions introduced Material Design.