Professional surveillance DVR can handle multiple video inputs simultaneously. Each video input is considered as one channel. A 16 channel DVR manages 16 different video inputs.
A 16 channel DVR with 16 surveillance cameras allows 16 different locations simultaneously. In general, you can monitor the video from each camera to record and read from a single console. If the camera is mounted on a motorized wall bracket, or have the special features such as zoom, it can be manipulated during recording or even to sweep areas automatically.