Editing System of units of measurement (section)

==Metric system==
{{Main article|Metric system|International System of Units}}
[[File:MetricImperialUSCustomaryUnits.jpg|thumb|upright|A baby bottle that measures in three measurement systems—metric, imperial (UK), and US customary]]

[[Metric system]]s of units have evolved since the adoption of the first well-defined system in France in 1795. During this evolution the use of these systems has spread throughout the world, first to non-English-speaking countries, and then to English speaking countries.

Multiples and submultiples of metric units are related by powers of ten and their names are formed with [[SI prefix|prefixes]]. This relationship is compatible with the decimal system of numbers and it contributes greatly to the convenience of metric units.

In the early metric system there were two base units, the [[metre]] for length and the [[gram]] for mass. The other units of length and mass, and all units of area, volume, and derived units such as density were derived from these two base units.

[[Mesures usuelles]] ([[French language|French]] for ''customary measures'') were a system of measurement introduced as a compromise between the metric system and traditional measurements. It was used in France from 1812 to 1839.

A number of variations on the metric system have been in use. These include [[gravitational metric system|gravitational systems]], the [[centimetre–gram–second system of units|centimetre–gram–second systems]] (cgs) useful in science, the [[metre–tonne–second system of units|metre–tonne–second system]] (mts) once used in the USSR and the [[metre–kilogram–second system of units|metre–kilogram–second system]] (mks). In some engineering fields, like [[computer-aided design]], millimetre–gram–second (mmgs) is also used.<ref>{{Cite web |title=Units and Dimension Standard - 2021 - SOLIDWORKS Help |url=https://help.solidworks.com/2021/english/SolidWorks/sldworks/hidd_units_dim_std.htm |access-date=2024-01-11 |website=help.solidworks.com}}</ref>

The current international standard for the metric system is the [[International System of Units]] ({{Lang|fr|Système international d'unités}} or SI). It is a system in which all units can be expressed in terms of seven units.  The units that serve as the [[SI base unit]]s are the [[metre]], [[kilogram]], [[second]], [[ampere]], [[kelvin]], [[mole (unit)|mole]], and [[candela]].