Perimeter security can be defined as systems and technologies that protect people and assets within a facility and its grounds by blocking unauthorised physical intrusions across the perimeter.

Systems should be equipped to protect the boundary and should comprise: the holistic site and property perimeter, eg the fence line; the inner territory perimeter, eg specific buildings or key infrastructure; the buildings perimeter, ie the external building shell; and the internal perimeter, eg internal space where restricted access is necessary. Each layer should help deter and detect intrusion.

Advanced technology has helped increase the scope of perimeter security systems, perimeter security solutions are now being used in areas such as commercial and residential sites, retail spaces, transportation sites, and many other urban and remote locations.