In various contexts of
science,
technology, and manufacturing (such as
machining,
fabricating, and
additive manufacturing), an
indicator is any of various instruments used to accurately measure small distances and
angles, and them to make them more obvious. The name comes from the concept of to the user that which their naked eye cannot discern; such as the presence, or exact quantity, of some small distance (for example, a small height difference between two flat surfaces, a slight lack of
concentricity between two cylinders, or other small physical deviations).