Several system of units have been used for describing measurements of the various physical quantities. Each system is named in terms of its fundamental units.

1) CGS System

It is known as Gaussian system and is based on 'centimeter', 'gram',and 'second' as fundamental units of length, mass and time respectively.
It is a metric system because multiples and sub-multiples of fundamental units are obtained in "power of ten" of the corresponding fundamental unit.

2) FPS System

It is the British system which uses foot, pound, and second as fundamental units of length, mass and time respectively. It is not a metric system and is rarely used.

3) MKS System

It uses metre, kilogram, and second as fundamental units of length, mass and time respectively. It is also a metric system.

4) SI (Systeme International d Unites)

The system was internationally accepted in 1960. SI is the abbreviation of 'Systeme International d' unites, which is French equivalent of International System Of Units.

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