Here's a breakdown:

* Pronation is the inward rolling motion of the foot, where the arch flattens and the ankle rolls inward.

* Supination is the outward rolling motion of the foot, where the arch lifts and the ankle rolls outward.

Think of it this way:

* Pronate: "Palm down" - Your hand faces the ground with your palm facing downward.

* Supinate: "Palm up" - Your hand faces the ceiling with your palm facing upward.

This same concept applies to the feet.