Reverse Engineering can be defined as the process wherein a device's, object's, or system's technological principles are discovered by analyzing its operation, function, and structure. It often refers to detaching something, say- a software program, electronic equipment, or mechanical device and carrying out the analysis of its workability in detail. This is done in order to manufacture a new program or device which performs the same function without doubling anything from original.

Motivation: Reasons behind the emergence of reverse engineering include interoperability, lost documentation which means loss or non-existence of documentation of the concerned device, product analysis, security auditing, exclusion of protection of copy, circumvention of restrictions regarding access, and fraud.

‘Reverse Engineering' of ‘mechanical devices' : With the ever-increasing popularity of CAD, ‘reverse engineering' has proven to be a blessing for creation of ‘3D virtual model' of the on hand physical part to be used in 3D CAE, CAM, CAD and many other soft wares. The measuring of physical object can be done by making use of ‘#D scanning technologies' such as computed tomography, ‘structured light digitizers', laser scanners, and CMMs. The data that is measured usually gets represented as ‘point cloud'. It is devoid of topological information. That's why, the processing and modelling takes place into usable format like a ‘triangular faced mesh', CAD model, or a collection of surfaces of NURBS. Applications such as Polyworks, Image ware, Geomagic, or Rapidform are used for processing the ‘point clouds' into the formats that can be used in applications like 3D CAE, CAM, CAD or visualization.

‘Reverse Engineering' of ‘software' : The term ‘reverse engineering' differs from person to person when applied in terms of software. As per the research conducted by Cross and Chikofsy, reverse engineering can be referred to as the process that involves the analysis of the subject system for creating its representation at the higher level. This level might be called the ‘level of abstraction'. As far as software is concerned, reverse engineering can be described as an examination process only. There is no modification from the software point of view. The use of ‘software anti-tamper technology' takes place in order to deter reengineering and reverse engineering of the software-powered systems and proprietary software.

Two major reverse engineering types exist in the present scenario. In the first type, source code is available, but program's greater level aspects are poorly documented or invalidated. In the second type, source code does not exist. Any efforts made in this direction would be termed as ‘reverse engineering'. The 2nd use is that which majority of people know. ‘Reverse Engineering of software' is implied at making use of ‘clean room design' technique for avoiding infringing copyrights. In today's world, around 95% of reverse engineering consists of ‘reverse engineering of software'.

On the other hand, ‘black box testing' in ‘software engineering' has many similarities to reverse engineering. The tester normally possesses the API. However, their main goal is to locate undocumented features and bugs by smashing the products from the outside. This process is used for customizing the embedded systems as well.