What is a CMM and how is it used in manufacturing?

A Coordinate Measuring Machine (CMM) is a precision device that measures the geometry of physical objects by sensing discrete points on surfaces using a probe. CMMs can measure dimensions, form, and position of features with accuracy up to micrometers. They are used for first article inspection, in-process quality checks, reverse engineering, and comparing manufactured parts against CAD models. Modern CMMs can be manual, CNC-controlled, or use optical/laser scanning.