An exponential function is a nonlinear function that has the form of y=a*b^x, where a != 0, b > 0. An exponential function with a > 0 and b > 1, like the one above, represents an exponential growth and the graph of an exponential growth function rises from left to right. An exponential function where a > 0 and 0 < b < 1 represents an exponential decay and the graph of an exponential decay function falls from left to right. When a quantity increases or decreases exponentially it increases or decreases by the same percent over equal time periods in comparison to when a compound increases or decreases linearly when a quantity increases or decreases with the same amount over equal time periods.