The metric system is a widely adopted decimalized system of measurement that derives from decimal numeral system being the consequence of us having 10 digits (fingers and thumbs).

Before the metric system became a standard in Europe, the local laws on measures were set by trade guilds on a city-by-city basis. In Switzerland, the survey of 1838 discovered that the foot had 37 different regional variations.

At the end of 18th century Louis XVI of France commissioned the group of scientists to develop a unified, practical and simple system of measurement to replace the disparate systems used back then. The scientists come up with the metric system that was derived from the properties of natural objects, i.e. the size of the Earth, the density of water, and relations between these. For instance, 1 meter was originally defined as 1/40,000,000th of the polar circumference of the Earth.

The metric system was officially adopted in France in 1791, after the French Revolution, and started to spread throughout the world, first to the non-English-speaking countries, and later to English-speaking ones. Today, only three countries, the United States, Liberia, and Burma have not adopted the International System of Units (SI) - the internationally recognized standard metric system since 1960.

The single international system of measurement is a great advantage for the international trade allowing applying common standards to goods and avoiding conversion errors, such as the one made by NASA in 1999 when it lost a $125 million Mars orbiter because one engineering team used metric units while another used Imperial units in their calculations.

See the map of countries by date of metrication