x？ Where x is called the base and 2 is called the exponent (the number in the upper right corner can be unknown).

Exponential function: y = a x(a >；; The function (x∈R) of 0 and a≠ 1 refers to power, a is constant and x is unknown.

Power function: the function of y = x a (a is a real number), that is, the power with the base as the independent variable, a as the constant and x as the unknown.