The international system of units (abbreviation SI) is the modern version of the metric system. It was created in 1960, and it is based on seven base independent values, which cannot be obtained one from the other or from the reciprocal transformations, here they are: kilogram, meter, second, ampere, Kelvin, mole and Candela. Units are divided into two classes - base and derivative. Base units are independent physical quantity. Derivative units are obtained by algebraic transformations of the base values. SI system is not static and it continues to evolve to match the more stringent requirements of the world needs in measurements.

### Base units

Name | Symbol | Value | Value symbol | Dimension symbol |

Meter | m | Distance | l, x, r | L |

Kilogram | kg | Mass | m | M |

Second | с | Time | t | T |

Ampere | А | Electric current | I | I |

Kelvin | К | Thermodynamic temperature | T | Θ |

Mole | mole | Amount of substance | n | N |

Candela | cd | Luminous intensity | Iv | J |