Which Android version introduced picture-in-picture mode?

Android 8.0 Oreo introduced picture-in-picture mode for Android phones and tablets.

Picture-in-picture, or PiP, lets an activity shrink into a small movable window while another app occupies the rest of the screen. It was particularly useful for video playback, video calls, and navigation because users could keep watching or following directions while browsing elsewhere.

Android 7.0 Nougat had already introduced the underlying multi-window framework and offered PiP on selected Android TV devices. Oreo made picture-in-picture available to regular Android handheld devices, turning it into a broadly usable phone and tablet feature.

For developers, Android 8.0 added the PictureInPictureParams object and manifest support for activities that could enter PiP. A common mistake is to treat PiP as the same feature as split-screen: both are multi-window modes, but split-screen gives two apps substantial screen regions, while PiP keeps one activity in a small overlay.