Visual testing (VT) is the oldest and most common nondestructive testing (NDT) techniques. It is typically the first step in the examination process to inspect a variety of product forms including castings, forgings, machined components and weld elements.

Compared to other techniques, visual testing is low in cost and easy to apply, and often eliminates the need for further types of testing. Some of the industries that use VT include structural steel, automotive, petrochemical, power generation, and aerospace.

Visual inspection is the process of examination and evaluation of systems and components by use of human sensory systems aided only by mechanical enhancements to sensory input such as magnifiers, dental picks, stethoscopes, and the like. The inspection process may be done using such behaviors as looking, listening, feeling, smelling, shaking, and twisting.

It includes a cognitive component wherein observations are correlated with knowledge of structure and with descriptions and diagrams from service literature