1. Measurement must depend on rules called standards. Things are measured based on comparison to standards2.The SI was made to establish an international standard, applicable anywhere. It is based on seven based units, the set on which all other SI units are derived from.3. Physics depends on measurements, and measurements depend on standards. Measurements and standards are in place to establish consistency and accuracy, and to aid communication and comparison. Units are the standards chosen to represent quantities. Units can be derived from other units and converted into other ones.