A dial indicator is a precision measuring instrument used to measure small distances or variations in height. It features a dial face with a needle that moves in response to a probe, which contacts the surface being measured. The dial typically displays measurements in millimeters or inches, allowing users to easily read the results. These instruments are commonly used in fields such as engineering, manufacturing, and machining to ensure accuracy in parts and assemblies. A gage block or a surface plate may be used in conjunction with a dial indicator to provide a stable reference point for measurements.