Non-destructive testing (NDT) is a group of analysis technique used in industry to evaluate the properties of a material, component or system without causing damage. The terms Nondestructive examination (NDE), Nondestructive inspection (NDI), and Nondestructive evaluation (NDE) also are commonly used to describe this technology. Because NDT does not permanently alter the article being inspected, it is a highly valuable technique that saves both money and time in product evaluation, troubleshooting, and research. Common NDT methods include Visual inspection (VI), liquid penetrant, magnetic-particle, ultrasonic, radiographic, eddy-current testing etc. NDT is a commonly used in forensic engineering, mechanical engineering, electrical engineering, civil engineering, systems engineering, aeronautical engineering, medicine, etc.