"Computer forensics is coming of age. Having been considered a 'dark art' practiced by underground types, it is now a maturing professional discipline and a critical factor in law enforcement and investigations. With the everyday prevalence of information technology, security operations must now take into account the technology aspects of a protective or assurance program and therefore include a view of computer forensics (also known as digital forensics) in developing tactical preparedness. The material of computer forensics is ESI (electronically stored information). That is information stored using digital devices. Computers are digital devices, as are mobile phones, digital cameras and GPS (global positioning system) navigation units. The basic function of computer forensics is to identify, preserve, collect, analyse and report on ESI evidence."