1. SI (International System of Units): This is the most widely used system globally and is based on seven base units: meter (m) for length, kilogram (kg) for mass, second (s) for time, ampere (A) for electric current, kelvin (K) for temperature, mole (mol) for amount of substance, and candela (cd) for luminous intensity.
2. CGS (Centimeter-Gram-Second): This system uses centimeter (cm) for length, gram (g) for mass, and second (s) for time. It is still used in some specific fields, particularly in astronomy and electromagnetism.
3. FPS (Foot-Pound-Second): This system uses foot (ft) for length, pound (lb) for force, and second (s) for time. It's primarily used in the United States and some other countries.
4. MKS (Meter-Kilogram-Second): This system is a predecessor to the SI system and uses meter (m) for length, kilogram (kg) for mass, and second (s) for time. It's less commonly used now as SI has become the standard.
It's important to note that all these systems are interconnected and can be converted between each other. The choice of system often depends on the field of study, historical context, and practical considerations.
