There are four system of units:
（i) F.P.S.(Foot-Pound-Second) system.
（ii) C.GS. (Centimetre – Gramme – Second) system.
（iii) M.K.S.(Metre-Kilogramme-Second) system.
（iv) S.I. (System International or International System).
（i) F.P.S. System: In this system, the units of length, mass, and time are foot, pound, and second
respectively.
（ii) C.G.S.System: In this system, the units of length, mass, and time are centimetre, gram and
second respectively.
（iii) M.K.S.System: In this system, the units of length, mass, and time are metre, kilogram and
second respectively.
（iv) S.I. units or International system of units: S.I. is based on seven basic units and two
supplementary units.