Picture-in-picture mode is a feature that allows users to watch a video in a small window while simultaneously using other applications on their device. This mode is commonly found in video streaming services and video conferencing apps, enabling multitasking without interrupting the viewing experience. When activated, the video window can be resized and moved around the screen, providing flexibility in how users interact with their content. This feature is available on various devices, including smartphones, tablets, and computers, making it easier to stay engaged with videos while performing other tasks.