A centimeter is the equivalent of 25/64 inch, and 3 centimeters is the equivalent of 1 3/16 inches. Centimeters are the smallest unit of the metric system, which is a widely used measurement system that has been adopted around the globe. The United States is the only industrialized nation in the world that has yet to adopt the metric system as its own, although it was officially sanctioned for use in 1866.
The metric system is officially called the International System of Units. Nearly every country in the world uses it, with the exception of the United States, Burma and Liberia. In some countries, it is only partially put into service. For example, in the UK, the system is used for official measurements, but the imperial system of measure is used in most homes.
The metric system has its roots in the late 1500s when Simon Stevin, a Flemish mathematician published a pamphlet called "De Thiende," which translates to "the tenth." Stevin declared the use of decimals important in coinage, measures and weights.
Although not used widely in the U.S. among citizens, the metric system is useful in military and science and in some parts of industry. Customary units are more common in household uses, however.