Inflection point - Wikipedia
https://en.wikipedia.org/wiki/Inflection_pointIn differential calculus and differential geometry, an inflection point, point of inflection, flex, or inflection (British English: inflexion) is a point on a smooth plane curve at which the curvature changes sign. In particular, in the case of the graph of a function, it is a point where the function changes
Inflection points introduction (video) | Khan Academy
www.khanacademy.org › ab-5-6a › vInflection points are points where the function changes concavity, i.e. from being "concave up" to being "concave down" or vice versa. They can be found by considering where the second derivative changes signs. In similar to critical points in the first derivative, inflection points will occur when the second derivative is either zero or undefined.