It capture images in much the same way as a digital camera, and compress the files to transmit over the network. It may be used with a wired network connected via ethernet cable to a broadband modem or router, or wirelessly via a WiFi router
Though IP is an abbreviation for Internet Protocol, it will work perfectly fine without an internet connection. You can view the cameras, record to a hard drive, and search through recorded footage using just a monitor and a mouse plugged directly into the NVR.
CCTV systems convert the video signal to a format that can be used by televisions, VCR’s, or DVR’s. IP cameras convert the video signal into IP packets to be transmitted over the data network or internet to a network storage device such as a server, NAS, or by storing on board the camera.