In mathematics, a fundamental concept of differential calculus representing the instantaneous rate of change of a function .
The first derivative of a function is a function whose values can be interpreted as tangent lines to the graph of the original function at a given point. The derivative of a derivative (known as the second derivative) describes the rate of change of the rate of change, and can be thought of physically as acceleration. The process of finding a derivative is called {{link=differentiation">differentiation .