The metric system is the primary system of measurement used through much of the world and in science.Each type of measurement has a base unit to which prefixes are added to indicate multiples of ten.

The metric system is a called a decimal-based system because it is based on multiples of ten. Any measurement given in one metric unit (e.g., kilogram) can be converted to another metric unit (e.g., gram) simply by moving the decimal place. For example, let's say a friend told you that he weighed 72,500.0 grams (159.5 lbs). You can convert this to kilograms simply by moving the decimal three places to the left. In other words, your friend weighs 72.5 kilograms.