- The units we use for measurement are called SI units.
- These units are specified by the International Bureau of Weights and Measures.
- There are seven base SI units. The magnitude of these units is specified by the measurement of a physical property under specific conditions.
- All the other SI units are derived from these base units.
- The quantities which are measured by the base units are called base quantities.
- The quantities measured by derived units are called derived quantities.