Visual Testing involves the visual observation of the surface of a test object to evaluate the presence of surface discontinuities such as corrosion, misalignment of parts, physical damage and cracks.

Visual testing can be done by looking at the test piece directly, or by using optical instruments such as magnifying glasses, mirrors, borescopes and computer-assisted viewing systems. VT can be applied to inspect castings, forgings, machined components and welds and is used in all branches of industry.