Definition - What does International System of Units (SI) mean?
The International System of Units (SI) is considered the modern form of the metric system and is now the most widely used system of measurement in the world. It is used both in science and in everyday commerce. The standard was based on the meter-kilogram-second (MKS) system and was published in 1960 as a result of the initiative that started in 1948. It is part of the International System of Quantities.
Techopedia explains International System of Units (SI)
The International System of Units consists of coherent systems of measurement built around 7 base units, 22 named and a number of unnamed coherent derived units, and a set of prefixes that serve as decimal-based multipliers.
It is declared as an evolving system, so there can be new units and prefixes created, and even unit definitions can be modified through an international agreement as the technology and precision of measurements improve.
All SI units can be expressed directly or in terms of standard multiples or fractional quantities by powers of 10 ranging from 10-24 to 1024.