A Network Video Recorder (NVR) is a internet protocol (IP) based video surveillance system or software that is designed to record and playback the video from IP cameras. Unlike DVRs (Digital Video Recorder), typically NVRs do not have video compression engines on board for the video is digitized, processed and compressed by its IP cameras, and then transmitted to the NVRs over IP network. But, the NVRs should decode both live video stream and playback video stream.

Usually, the NVRs support multi-channel video display, flexible recording schedule with different video profile with playback capability, a user friendly GUI, intelligent event detection and notification, remote monitoring and control, and PTZ camera control, etc.

There is a similar, but different network video recorders called Network Storage Recorders(NSRs). Typically, NSRs do not have video output, and all the operations are done over the IP network. So you need to use a PC to access the live or recorded video.