Metrology is the science of measurement. It includes units of measurement and their standards, measuring instruments and their field of application, and all theoretical and practical aspects relating to measurement.
Metrology is classified in three main fields:
Scientific Metrology is that part of metrology which deals with aspects common to all metrological questions irrespective of the quantity measured. It covers general theoretical and practical problems concerning units of measurement, including their realization and dissemination through scientific methods, the problems of errors and uncertainties in measurement and the problems of metrological properties of measuring instruments.
There are different specialist areas of metrology, for example:
Industrial Metrology is that part of metrology which deals with measurements in production and quality control. It covers calibration procedures, calibration intervals, control of measurement processes and management of measuring instruments in industry to ensure that they are in a state of compliance with requirements for their intended use.
Legal Metrology is that part of metrology which is subject to legal/regulatory control. It is defined in the International Vocabulary of Legal Metrology as that part of metrology relating to activities which result from statutory requirements and concern measurement, units of measurement, measuring instruments and methods of measurement and which are performed by competent bodies.
Legal metrology provides regulations for the control of measurements and measuring instruments. Legal metrology provides protection of public safety, the environment, consumers, traders and is critical to fair trade.