# What is Metrology definition/concept/elaboration

In everyday life we take measurements in a very usual way. For example, we weigh the fruits when we go to buy them, we observe the speed of our vehicle and we also measure the body temperature when we feel any physical discomfort. We need to measure accurately, otherwise we would not be able to objectively assess certain everyday situations. Metrology

In other words, our everyday decisions depend largely on the outcome of the measures we take.

It comprises a scientific branch focused on the study of the most varied measurement systems. It is an auxiliary science, as its data are applied in all scientific disciplines.

### General principles

This science has as main objective the correct evaluation of any measure. For this to be possible, a series of indicators or parameters must be taken into account . First, a repeated measure must always give equal results (in the language of metrology, this characteristic is known as repeatability).

On the other hand, there must be temporal stability in the measurements (when I measure something many times with the same instrument, the result must always be the same).

Obviously, the references or standards used have to be with known values (for example, the kilogram is a world-recognized standard).

One of the most important aspects in metrology is accuracy, that is, the measurement cannot have any type of error (for example, the standard kilogram is a prototype that can be found at the International Bureau of Weights and Measures, in Paris, and any object of one kilogram can be compared with the prototype of this organism).

It should be noted that there are patterns of all kinds of magnitude, whether physical or chemical.

### Several approaches and fundamental aspects

Like any other area of scientific knowledge, this discipline has several branches. There are three main ones: industrial metrology, scientific metrology and legal metrology.

In specific metrology terminology, specialized concepts are used: influence magnitude, true and nominal value, calibration, measurement reproducibility, maximum allowable error, measurement uncertainty, among others.

**Finally, it should be noted that there are three systems of measurement units: the metric system, the English system or USCS and the international system or SI**

– The metric system is based on two units, the meter and the kilogram.

– The English system is based on inches and yards.

– The SI is a modernized version of the metric system and has been in existence since 1960 (this measurement model uses the meter as a unit of length, the kilogram for the mass, the second for the time, the ampere for the electric current and the kelvin for the temperature).