Video is an electronic medium for the recording, copying, playback, broadcast, and display of moving-image media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) systems, which, in turn, were replaced by flat-panel displays. Video systems vary in display resolution, aspect ratio, refresh rate, color reproduction, and other qualities. Both analog and digital video can be carried on a variety of media, including radio, magnetic tape, optical discs, computer files, and network streaming. Source: Wikipedia (en)