Van der Waals forces generally aren’t noticeable in everyday life, as even two seemingly smooth, flat surfaces are rough enough at the microscopic scale to make them ineffective. But with many angled, flared-tip fibers lying flush with this rough terrain, van der Waals forces are strong enough for the gecko to stick to a wall. Changing the angle of their feet is what makes the gecko’s adhesion “tunable” and what allows them to detach from the wall to take each step.