Since the dawn of civilization, the need for measurement has been imperative. The ancient Egyptians used the "cubit" (the distance from the elbow to the tip of the fingers) to build the pyramids.

The Need for Standards

Before the International System of Units (SI), each region had its own measures. This made trade extremely difficult. The French Revolution brought a revolution in measurements as well, introducing the decimal system and the "Meter".

Today

Today, units are not defined by physical objects (like the old meter bar in Paris) but by universal constants of physics, such as the speed of light.