The Metric System, also known as the International System of Units, is a system of measurement used by most of the world. It is sometimes abbreviated as "SI", from the French "Système Internationale d'unités". It has been adopted by every country in the world except for the United States, Liberia, and Burma. In the United States, the metric system is used by scientists. The metric system uses seven base units, and other units can be derived from these base units. These base units are the meter, the kilogram, the second, the ampere, the candela, the mole, and the degree. For temperature, Celsius is used in everyday life. The Kelvin scale is used for scientific purposes.
SI units are organized in a very logical manner. For this reason, it is superior to United States customary units. All of the units are decimalized. For example, 1/100 of a meter is a centimeter, and 1000 meters is a kilometer (That's just over 0.6 of a mile). The units also "fit together". For example, one gram is the weight of one cubic centimeter of water. Temperature units are also logical. On the Celsius scale, 0° is the exact temperature at which water freezes at standard pressure. 100°C is the exact temperature at which water boils at standard pressure.