In mathematics, the inflection point of a function is the point where the convexity of the curve on its graph changes. Specifically, if at a certain point the left curve is convex (curved upward) and the right curve is concave (curved downward), or vice versa, then this point is the inflection point. The existence of inflection point indicates that the derivative (slope) of the function has changed at this point. In practical application, inflection point is often used to analyze the changing trend of data, such as the inflection point of economic data, indicating that the trend has changed from growth to decline, or from decline to growth. On images, inflection points usually show significant changes in the shape of curves.