The International System of Units (SI System)
The SI system is the international system of units, that specifies the basic units used in measurement science. SI system determinates 7 base units (meter, kilogram, second, ampere, kelvin, mole and candela) and 22 derived units. The base units are derived from constants of nature.
The SI system is maintained by the BIPM (Bureau International des Poids et Measures).
More information on the SI system can be found at BIPM website: