A CMM (Coordinate Measuring Machine) is a testing device used to measure the geometric properties of physical objects with high precision. These machines collect various points from the surface of the object using a probe and calculate distances, angles, and other geometric data between those points. CMM devices are commonly used in quality control processes, particularly in the automotive, aerospace, and engineering industries, to verify the dimensional accuracy of complex parts. They can operate manually, semi-automatically, or fully automatically, providing precise measurement and quality standards in production processes.