The term indices refer to the power to which a number is raised. The power or exponent is generated by repeated multiplication, for example 2×2×2×2 = 24, here 2 is known as the base and 4 is known as the power or exponent. In general, \(a \cdot a \cdot a....\;m\;{\rm{times}}\; = {a^m}\).

Sometimes the power or exponent becomes a fraction, the indices is known as a surd such as \({2^{1/2}} = \sqrt 2 ,\;{3^{1/3}} = \sqrt[3]{3}\) etc.