A lever arm is the distance between the fulcrum (the point around which a lever rotates) and the point where the force is applied. The longer the lever arm, the greater the mechanical advantage of the lever, which means that a smaller force can be used to move a larger load. Lever arms are an important concept in physics and engineering, and are used in the design of many simple machines like scissors, crowbars, and seesaw. The length of the lever arm directly affects the amount of torque (rotational force) that can be generated.