A micrometer is a precision measuring instrument used to measure small distances and thicknesses with a high degree of accuracy. It consists of a spindle that is moved towards a fixed anvil using a calibrated screw, and the measurement is read from a scale or a digital display. Micrometers are commonly used in manufacturing, engineering, and scientific fields to measure the diameter of a part, the thickness of a material, or the distance between two points. They come in various forms, including outside micrometers for measuring the diameter of a cylindrical object, inside micrometers for measuring the diameter of a hole, and depth micrometers for measuring the depth of a hole or groove.