Metrology, or the science of measurement
Metrology is the discipline that defines the procedures for correctly performing the measurements.
It therefore deals with the measurement of any object, in both theoretical and practical aspects; in summary, it includes both methodologies and instruments used to attribute a measure to a certain quantity. This science includes more disciplines within it, since it is concerned with measuring any physical quantity: from mathematics to electronics, from mechanics to physics. It applies to any field, from technology to art such as music (measurement of time, intensity of sound…).
This is because measurement is the process that deals with obtaining values through experimentation in order to attribute them to a quantity. Quantity is in fact a property of the phenomenon that is measured and expressed through a number and a reference (unit of measurement).

What is metrology for?
Metrology is used to make the parameters employed for measuring physical quantities unique. To date, industrial production would not be possible without fixed and shared units of measurements, without uniform and univocal control tools.
Similarly, measurement tools are tested and calibrated each time, before starting operation, so that they are regularized according to world standards.
Legal metrology
Legal metrology deals with the traceability chain for consumers and producers, with standard criteria for the use of the instrumentation and the correct control and verification procedures.
Furthermore, it deals with the instrument calibration procedure, thus having a fundamental role in carrying out any production activity and commercial exchange at an international level.