What is notation for second derivative?

The second derivative of a function y with respect to x is denoted by y'' or d²y/dx². It represents the rate of change of the rate of change of y with respect to x. The notation y'' is read as "y double prime" or "y second derivative." The notation d²y/dx² is read as "the second derivative of y with respect to x" or "the derivative of dy/dx with respect to x." The second derivative is important in calculus as it helps in determining the concavity and points of inflection of a function.