Security systems are comprised of a number of components, each of which has a role in forming a security solution. A video surveillance system will have most of these components, connected as shown below:

• Camera- the device that captures moving images through its lens
• VCR (Video Cassette Recorder)- a device that records video from a camera onto a magnetic tape
• DVR (Digital Video Recorder)- a device that records video from analog and/or digital cameras onto a hard disk that is randomly accessible for playback, and that may be connected to a communication network
• NVR (Network Video Recorder)- a device on an IP-network that can record video images from a set of IP-cameras connected on a network, and provide access to live and stored video over the network