In general, Reverse engineering (RE) is the process of taking something (a device, component, an electrical component, a software program, etc.) apart and analyzing its workings or geometry in detail, usually with the intention to construct a new device, component or program that does the same thing without actually copying anything from the original.
Reverse engineering is a often used by military, in order to copy other
nations' technology, parts of which have been obtained by intelligence
operations. It was often used during the Second World War and Cold War.
Reverse engineering software or hardware systems for the purposes of
interoperability, for example in order to support undocumented file formats or
hardware peripherals, is mostly believed to be legal, though patent owners often
aggressively pursue their patents.
Coordinate-measuring machines (CMM) can be used to digitize a component and the
information can be utilized in computer-aided modeling. New and improved
techniques in reverse engineering include 3D laser scanning which, as the name
implies, uses laser beams to scan across the surface of components of any shape
and display the results in real time.