Metric system
The metric system is a decimal-based system of measurement. The system has units of measure for each quantity. The names of most units of measure in the metric system have two parts. One part is the unit name and the other part is the prefix. For example, in the name "centimetre", the word "centi" is the prefix and the word "metre" is the unit name. Sometimes, as with metre, litre and gram, there is no prefix.