measurementSystem

A measurement system, or measurement system of units, is a framework that defines the units and rules used to quantify physical quantities. It provides a coherent set of base quantities, base units, and derived units, along with prefixes that scale unit magnitudes. The system specifies how quantities are combined and how measurements are reported, enabling clear communication and comparison of results across contexts.

Base units are the fundamental quantities from which others are derived. The International System of Units (SI) is the modern globally adopted measurement system. It defines seven base units: second for time, metre for length, kilogram for mass, ampere for electric current, kelvin for temperature, mole for amount of substance, and candela for luminous intensity. Derived units are formed by combining base units, such as newton for force (kg*m/s^2) and joule for energy (kg*m^2/s^2). The system uses prefixes, such as milli-, micro-, and kilo-, to express multiples and submultiples of units.

Other measurement systems include the British imperial system and the US customary units, historically prevalent in some regions, and the centimeter-gram-second (CGS) system used in some fields. SI has become the internationally preferred system for science, industry, and commerce due to its coherence and universality, with ongoing revisions to definitions based on fundamental constants (for example, redefinitions of the kilogram and ampere in 2019).

Measurement systems support traceability, calibration, and uncertainty analysis. Measurements are linked to national and international standards through a chain of calibration that establishes confidence in reported values. Proper use of a measurement system ensures consistency, comparability, and interoperability of data across instruments and applications.

In practice, measurement systems underpin research, engineering design, quality control, logistics, and data analysis. They are foundational to standardization efforts, metrology institutions, and the global exchange of quantitative information.