A micrometer is a precision measuring instrument used to measure small distances or thicknesses with high accuracy. It typically has a screw mechanism that allows for measurements in increments of one thousandth of a millimeter, or one micrometer (µm). Micrometers are commonly used in mechanical engineering, manufacturing, and scientific research to ensure precise measurements of components. 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 depth. These tools are essential for quality control and ensuring that parts meet specific tolerances.