Unit system

A system of Units is a consistent, standardized, and uniform set of units of measurement. In general they define a few units of measure from which the rest are derived. There are several systems of units:

• International Unit System (IS): the modern version of the metric system and the most used today. Its basic units are: the metro, the kilogram, the second, the amperio, the kelvin, the candela and the mol. The other units are derived from those.
• Decimal metric system: first unified measurement system. Its basic units are: the metro and the kilogram.
• Cegesimal Unit System (CGS): so called because its basic units are centimeter, gram and second. It was created as an extension of the metric system for scientific uses.
• Natural System: in which the units are chosen so that certain physical constants are worth exactly the unit.
• Technical Unit System: derived from the metric system with units created for technical uses and based on the previous one. This system is in disuse.
• Anglo-System Units: It is the traditional Anglo-Saxon system. In 1824 it was normalized in the UK with the name of Imperial System, whose use remains in the ordinary life of this country. It was also standardized in the United States, with some differences over the Imperial System, and the latter is only used as a legal system in the United States and Liberia.
• MKS Unit System: Expresses the measures using as fundamental units metro, kilogram and second (MKS). The MKS unit system laid the foundation for the International Unit System, which now serves as an international standard.

In addition to these systems, there are practical units used in different fields and sciences. Some of them are:

• Atomic units
• Units used in Astronomy
• Mass units
• Energy measurement units