Smallest to Largest that we deal with:
A nanosecond (ns) is a SI unit of time equal to one billionth of a second
A microsecond is an SI unit of time equal to one millionth (0.000001 or 10−6 or 1/1,000,000) of a second. Its symbol is μs.
A millisecond (from milli- and second; symbol: ms)
The second (symbol: s) (abbreviated s or sec) is the base unit of time in the International System of Units (SI).[