Is the agreement of the result of a measurement with the true value of the measured quality. Modern civilization would be impossible without a good set of established standards to manufacture products by.
Calipers come in various configurations but there are three common styles.
Vernier, Dial and Electronic. These three types are similar in construction and general appearance but vary in function and ease of use. Each has their own strengths and weaknesses which must weighed before selecting the appropriate equipment. Later, the 50 grad style was introduced to expand the graduations and make it much easier to see without the use of an eyepiece. Here lies the shortcoming of the tool.