The NVR or Network Video Recorder is a stand alone recorder for use with IP or WIFI network cameras. NVRs are available to support from 4 cameras up to over a hundred IP network cameras.
Some NVRs have built in Poe ports to allow them to provide power as well as communication for the camera in a single cable.
Some NVRs are sold without hard drive so you can add your own, while others come with a hard drive pre-installed.
We typically recommend the use of an NVR instead of software based recording when stability or ease of use is important. Also known as an embedded NVR, these stand alone systems run their own internal operating system rather than relying on windows.