International System of Units The International System of Units
is a system of measurement based on 7 base units: the metre
(length), kilogram (mass), second (time), ampere (electric
current), Kelvin (temperature), mole (quantity), and candela
(brightness). These base units can be used in combination with
each other. This creates SI derived units, which can be used to
describe other quantities, such as volume, energy, pressure, and
velocity. The system is used almost globally. Only Myanmar,
Liberia, and the United States do not use SI as their official
system of measurement. In these countries, though, SI is
commonly used in science and medicine. History and use [change]
The metric system was created in France after the French
Revolution in 1789. The original system only had two standard
units, the kilogram and the metre. The metric system became
popular amongst scientists. In the 1860s, James Clerk Maxwell
and William Thomson (later known as Lord Kelvin) suggested a
system with three base units - length, mas