The calibration result is the relationship between the indications of a measurement instrument or measurement system and the values indicated by the standard. It is possible that this measuring instrument, also called an “object of calibration,” can be used as a standard for calibrating other measuring instruments once calibrated. The national accreditation body should preferably accredit laboratories that perform calibrations. Unaccredited laboratories can also calibrate since they use standards that are traceable to national or international standards. In this chapter, we remember some concepts and address others, such as calibration, measurement standards, traceability, tolerance, verification, and other aspects that involve this theme. We perform calibration exercises on some measurement instruments.