Question

what is SI unit
and CGS unit

Answer 1

CGS stands for centimetres gram second system of units..
In CGS system the unit of length,mass and time are centimetres,gram and second respectively. .
In SI system the unit of length,mass and time are metere, kilograms and second. .

Answer 2

A system of physical units ( SI units ) based on the metre, kilogram, second, ampere, kelvin, candela, and mole, together with a set of prefixes to indicate multiplication or division by a power of ten. This  Is SI unit.

The centimetre–gram–second system of units is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time. This is CGS unit..