Hikvision NVR (network video recorders) are similar to a DVR with one major exception, the signal is carried digitally between the camera and the recorder (NVR) much like linking your office computers and mobile devices to your wifi at home whereas DVRs ( digital video recorders) only record the signal in digital format. This can be compared to the digital TV switchover which ended the "snowy" or ghosting pictures. The same applies to digital CCTV systems. Any CCTV product attached to the NVR has to be "network " or "IP" ( internet protocol) compatible.
Hikvision NVR with connection for IP cameras
The downside of IP CCTV systems is the cost, difficult to fault find if you don't have little some networking skills or cant use a computer. Also, you can't take out an NVR made by one manufacturer and replace it with another. The same applies to cameras.
Nearly all of our Hikvision NVRs have built-in PoE ( power over ethernet ) which means there is no need to buy a power supply to power the cameras as its built into the NVRs Only one cable is needed between the IP camera and the NVR, this cable is called CAT5 or network/ethernet cable as shown in the picture below. This cable can also carry sound and other control signals and also have additional devices connected to the IP cameras such as control relays for switching other devices.