A calibration target is a “thing” that provides a specific value of a quantity with high precision, which is used to calibrate a “device under calibration”. For example, a calibration target could be a piece of metal providing a very precise distance of 10cm between its edges. Therefore, it can be used to calibrate the quantity “length” of a sensor measuring the distance between these edges. A calibration target can also be a device providing a quantity. For example, a precision voltage source used to calibrate a voltage meter.