Centrifugal force is an inertial (pseudo or fictious) force used in a non-inertial frame of reference in order to apply the Newton's laws of motion. If your question is about centripetal force, which is a real force that points towards the center of a circular trajectory, use the tag "centripetal-force" instead.

A centrifugal force is any real force that pushes or pulls away from the center of a rotating system. When you're a passenger in a car, and the car rounds a curve, you feel yourself pushed away from the center of the curve. That push is merely the straight line of your inertia colliding with the curving path of the car around you.

However, as the car shoves you into its curved path, your body shoves back against the car (your equal and opposite reaction). That's a centrifugal force: Not the imaginary something seeming to act outward on you, but you pushing outward against the car, and the car's tires pushing against the road, and the road bed pushing outward against whatever supports it... such as the bridge you could be designing someday. Please make sure it can withstand that lateral force; if you dismiss all centrifugal forces as imaginary, then your bridge could collapse and fall over.