We must understand the meaning of acceleration of moving bodies before trying to understand the centripetal acceleration. A body that moves equal distances in equal intervals of time in a specific direction has uniform or constant velocity and zero acceleration. The moving body has an acceleration when it either changes its direction of motion or the magnitude of the velocity or both. The rate of change of velocity is acceleration.
Consider a body which is ...
This article is helpful in understanding centripetal acceleration and centripetal force and written specially for those who are confronting the idea for the first time.