Visual testing or inspection serves to locate and evaluate the superficial quality traits of the object (discontinuities and deformations) either with the naked eye or with the use of instruments (optical, electronic, mechanical gauges etc.).

External visual testing or inspections is conducted with the use of control and measurement equipment, such as weld gauges, calipers, rules, magnifying glasses, etc.

Internal visual testing of objects such as tanks is conducted with the use of endoscopes and coating gauges.