Visual inspection is a type of nondestructive testing (NDT) method that uses the human eye to detect and evaluate defects in materials or components. Visual inspection is performed by trained and certified personnel, who use their eyesight, along with specialized lighting and inspection aids, to examine the surface of the material or component being tested.

Visual inspection is commonly used to detect surface defects, such as cracks, voids, inclusions, or corrosion, that may affect the strength or performance of the material or component. Visual inspection can also be used to evaluate the condition of coatings, such as paint or plating, and to verify that the material or component meets specified dimensional or visual requirements.

Visual inspection is a cost-effective and versatile NDT method, and can be performed on a wide range of materials and components, including metals, plastics, ceramics, and composites. However, visual inspection is limited by the ability of the inspector to detect defects, and may not be suitable for detecting certain types of defects, such as those that are hidden or are not visible to the naked eye. As a result, visual inspection is often used in conjunction with other NDT methods to provide a more comprehensive evaluation of the material or component.