centripetal force is the force required to make an object rotate in a circular path of radius R and with an angular velocity w.. This force is directed towards the center of curvature of the circular path.
if a stone is tied to a string and whirled around in a circle, the tension in the string acts as the centripetal force.
Centrifugal force is a pseudo force. It does not exist actually. When a body in rotating or turning in a circular path, or when a body like Earth is rotating about itself, centrifugal force concept is used for solving problems and getting answers related to dynamics of objects in circular (or rotational) motion.
Inside the frame of reference of the rotating body, a force is said to be acting on each object with a mass, in the direction opposite to the direction in which the centripetal force should be acting. that is outwards along the radius of curvature of the circular path the object travels.