The metric system is an international system of measurement. It is one of two main systems of measurement in use today.

The British Imperial system includes units such as feet, pounds, gallons, and Fahrenheit degrees of temperature. This system was used in many of Britain's former colonies, including Canada.

The Imperial system was based largely on human dimensions, for example, the length of a human foot or the length of an arm (yard). The system did not seem to have any logical plan. For example, why should there be 12 inches in a foot, and only three feet in a yard?

The metric system has units such as metres (m), kilograms (kg), litres (L), and degrees Celsius (°C). It was introduced in France during the French Revolution at the end of the 18th century. It was logically planned. For instance, in the original metric system the metre was defined as being 10-millionth the distance between the Pole and the equator. In the latest version of the metric system, known as the Système International (SI), the metre is defined as the distance travelled by light in a vacuum in 1/299 792 458 second.

The main advantage of the metric system over the Imperial system is that it is easy to use. To convert from smaller to larger units, you simply multiply by multiples of ten. To convert from larger to smaller units you divide by multiples of ten. Thus a kilometre is 1000 metres, and a centimetre is one-hundredth of a metre.

"Kilo-" and "centi-" are examples of prefixes. By putting the appropriate prefix in front of a base unit, the metric system can be used to measure an enormous range of things. For instance, the metre can be divided to get a unit for measuring lengths as small as the diameter of an electron, or multiplied to get units big enough to measure the span of a galaxy.

For example, to get a multiple unit measuring 1000 metres, put the prefix "kilo" in front of the name of the basic unit "metre," to produce "kilometre."

The metric system is the system used everywhere in science and in medicine. It has been adopted by most countries in the world, except the United States.

Canada has been changing to the metric system of measurement since the 1970s. Metric units are now used in weather forecasts, road signs, speedometers, gasoline stations, and grocery stores. Nevertheless, many people cling to the traditional Imperial measurements that are familiar to them.

See also METRIC SYSTEM: TABLE.