Non-destructive examination (NDE) or nondestructive testing (NDT) is a family of technologies used during inspection to analyze materials, components and products for either inherent defects (such as fractures or cracks), or service induced defects (damage from use). Some common methods are visual, industrial computed tomography scanning, microscopy, dye penetrant inspection, magnetic-particle inspection, X-ray or radiographic testing, ultrasonic testing, eddy-current testing, acoustic emission testing, and thermographic inspection. In addition, many non-destructive inspections can be performed by a precision scale, or when in motion, a checkweigher. Stereo microscopes are often used for examining small products like circuit boards for product defects.