The metric system was designed in France in the 18th century. Before then, it was common for units of length, area, and weight to vary from one country to another and even within the same country. Length could be measured in feet, miles, spans, cubits, hands, furlongs, palms, rods or chains. The metric system brought order to the confusing systems of weights and measures then being used in Europe. In 1875, most industrialized countries signed the Treaty of the Meter which formed the International Bureau of Weights and Measures. We now call this system the International System of Units. Although the US uses this system for scientific measurement, most people still use the more complicated system that involves inches, feet, miles, cups, pints, quarts, ounces, and pounds. The United States, Burma, and Liberia are the only countries that do not routinely use the metric system
The meter is the standard unit of linear measure. One meter (39.4 inches) is roughly equivalent to one yard (3 feet). 1 kilometer (km) is 0.6 miles. A finger is measured in cm (2.54 cm in 1 inch). A micrometer (micron) is not visible by unaided human eye. Most cells are in the micron range. To see an object much smaller, an electron microscope must be used.
The gram is the basic unit for measuring mass. There are 0.454 kilograms in a pound.
The basic unit of temperature is degrees Celsius. Body temperature is 37 oC.
Volume is a three dimensional space occupied by a gas, liquid, or solid.
Liquid volume is measured in liters. One liter = 1.06 quarts.
The volume of a solid material is determined by multiplying length X depth X width to obtain a cubic number (c3)f