- SI stands for the ‘Système lnternational (SI) D’Unités’, which translates from the French as the ‘International System of Units’
- Represent a set of fundamental base units, derived units and prefixes used throughout the world:
- Based on metric units with the decimal system
- Definitions are not static and undergo frequent evolution
- The latest change in 2019 saw all definitions become based upon “constants” of physical sciences
- The need to create highly accurate and precise definitions has led to very complex definitions
- Adopted to overcome the use of diverse and inconsistently applied units and quantities that had developed in medicine
- Allows increased ease of communication and avoidance of errors and misunderstandings