SI Units

The international System of Units, SI, was adopted by the General Conference of Weights and Measures in 1960. In SI units six physical quantities are assigned unit value. The six quantities are:

length (meter, m)
mass (kilogram, kg)
time (second, s)
electric current (ampere, A)
thermodynamic temperature (degree kelvin, K)
luminous intensity (candela, cd)
All other physical quantities are derived from these; for example, velocity=length/time has units of m/s.