What are SI units and Explain about prefixes?

SI units:

The system of units used in engineering and science is the Systeme Inter-`nationale d’Unites (International system of units), usually abbreviated to SI units, and is based on the metric system. This was introduced in 1960 and is now adopted by the majority of countries as the official system of measurement.
The basic units in the SI system are listed with their symbols, in
Table below:

TABLE Of Basic SI Units:
Quantity /Unit,Symbol
length /metre, m
mass /kilogram, kg
time /second, s
electric current /ampere, A
thermodynamic temperature /kelvin, K
luminous intensity /candela, cd
amount of substance /mole, mol
Derived SI units:
Use combinations of basic units and there are many of
them. Two examples are:
1. Velocity — metres per second (m/s)
2. Acceleration — metres per second squared (m/s^2)
Prefixes:
SI units may be made larger or smaller by using prefixes which denote multiplication or division by a particular amount. The six most common multiples, with their meaning, are listed in the table below.
TABLE Of Prefixes:
Prefix /Name ,Meaning
M /mega ,multiply by 1 000 000 (i.e. ð 106)
k /kilo ,multiply by 1000 (i.e. ð 103)
m /milli ,divide by 1000 (i.e. ð 10 3)
μ /micro ,divide by 1 000 000 (i.e. ð 10 6)
n /nano ,divide by 1 000 000 000 (i.e. ð 10 9)
p /pico ,divide by 1 000 000 000 000 (i.e. ð 10 12)