DVR stands for Digital Video Recorder. A DVR is a device that records video in a digital format on a Hard Drive or another Media device. What most people think of when they hear DVR is the cable or satellite set-top box on their TV. The term also describes hardware and software for personal computers enabling video capture and playback to and from disk. Finally, and most importantly, DVR technology is the basis of video surveillance systems.
Digital video recordings do not use film. Like any other electronic data, digital video recordings are stored by the DVR to an electronic device, usually a hard drive. Unlike film, the resulting video from a DVR can be easily stored and reproduced. Digital video can also be viewed during playback in ways not possible with film, with capabilities like fast forwarding or reversing through a video recording even as it continues to record.
A PC configured as a DVR, like a surveillance system, commonly uses one or more cameras for a video source. A DVR without a video source has nothing to record. In this sense, a DVR can be thought of as a system of components a digital video source (or multiple digital video sources), an electronic recording mechanism (hard drives, mememory sticks) and software to control the recording, storage, and playback.
Closed circuit television (CCTV) has replaced analog VCR’s with digital video recorders. These electronic devices formerly stored images on magnetic videotape for playback. Video cassette recorders have been replaced by technology with digital video recorders. The result is a pure digital picture of the highest quality for playback, recording and video archiving.