The
International System of Quantities (ISQ) is a system based on seven base
quantities:
length,
mass,
time,
electric current,
thermodynamic temperature,
amount of substance, and
luminous intensity. Other quantities such as
area,
pressure, and
electrical resistance are derived from these base quantities by clear, non-contradictory equations. The ISQ defines the quantities that are measured with the
SI units and also includes many other quantities in modern science and technology. The ISQ is defined in the international standard
ISO/IEC 80000, and was finalised in 2009 with the publication of
ISO 80000-1.