lever is a machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum.
Levers are classified by the relative positions of the fulcrum and the input and output forces. It is common to call the input force the effort and the output force the load or the resistance. This allows the identification of three classes of levers by the relative locations of the fulcrum, the resistance and the effort.
The lever is a basically movable bar that pivots on a fulcrum attached to a fixed point. The lever operates by applying forces at different distances from the fulcrum, or pivot.
mechanical advantage of the lever: