CCTV is complicated and not just a case of buying and installing a camera.
Technology is advancing at a rapid rate and systems which historically were always analogue can now be analogue or digital.
Although data storage is now cheap and has caused digital systems to gain in popularity, the movement of large amounts of digital data can become a bottleneck, so due consideration needs to be given on how a system is planned to be used before deciding on the technology of the system.