Full form of CGS,

CGS: Centimetre Gram Second

Fundamental units are Centimetre, Gram and Second

MKS: Metre, Kilogram, Second

Fundamental units are Metre, Kilogram and Second

FPS: Foot, Pound, Second

Fundamental units are Foot, Pound and Second

SI: International System of Units

Fundamental units are Metre, Kilogram and Second

Some important conversions:

1 meter = 100 cm = 3.28084 feet

(Feet is plural of foot, that is more than 1 foot)

1 kg = 1000 g = 2.205 pound

1 second is same in all the units mentioned above