what is point of inflection?

point of inflection is a point in the given interval where second order derivative is zero.

                                                    f''''=0

point on the curve where the nature of curve changes and the point is differentiable.

in the above curve origin isthe point of inflection and the remaining portions are concave up and concave down graphs

Thus there are often points at which the graph changes from being concave up to concave down, or vice versa. These points are called points of inflection.