A Video Decoder is a device or software that converts compressed video files into a format that can be displayed on screens. When videos are recorded, they are often compressed to save space, which makes them difficult to play directly. The decoder takes this compressed data and translates it back into a viewable format, allowing users to watch videos smoothly. Video decoders are essential in various devices, including smartphones, computers, and televisions. They support different video formats, such as MP4 and AVI, ensuring compatibility across various platforms. Without a video decoder, playing back compressed video files would be impossible.