An exponential function is a nonlinear function that can be written in the following form, where $a\ne 0,$ $b>0,$ and $b\ne 1.$ As the independent variable $x$ changes by a constant amount, the dependent variable $y$ multiplied by a constant factor. Therefore, consecutive $y\text{-}$values form a constant ratio. Here, the coefficient $a$ is the $y\text{-}$intercept, which is sometimes referred to as the initial value. The base $b$ can be interpreted as the constant factor. The graph of an exponential function depends on the values of $a$ and $b.$