A micrometer is a precision measuring instrument used to measure small distances or thicknesses with high accuracy. It typically consists of a calibrated screw mechanism that allows users to measure objects down to one-thousandth of a millimeter (0.001 mm). Micrometers are commonly used in mechanical engineering, manufacturing, and scientific research. The most common type of micrometer is the outside micrometer, which measures the external dimensions of an object. There are also inside micrometers for measuring internal dimensions and depth micrometers for measuring depths. These tools are essential for ensuring precise measurements in various applications.