Raiography is the use of ionising electromagnetic radiation to view objects in a way that can't be seen otherwise. Radiography in general should not be confused with the use of ionizing radiation to change or modify objects; radiography's purpose is strictly for viewing. Industrial radiography has grown out of engineering, and is a major element of nondestructive testing (NDT). It is a method of inspecting materials for hidden flaws by using the ability of short wavelength electromagnetic radiation to penetrate various materials.