Levers at their most basic are a rigid beam attached to a fulcrum, or pivot point, and are very prevalent in everyday life. For example, doors and scissors as well as far more complicated things such as hydraulic lifts and engines all incorporate various types of levers.
Examples of levers that are encountered in everyday life include suspension and steering systems; anything with a hinge or ratchet incorporated into it; anything that is opened, such as a door or a jar of pickles; or even the human body with its network of bones, serving as beams, joints, analagous to fulcrums, and muscles, the equivalent of applied force, working together. Anything that incorporates a fulcrum and a rigid beam with an applied force in order to move a load is one of three types of levers depending on the location of the fulcrum, load and applied force relative to one another.
One of the six classical simple machines and fundamentally the simplest mechanisms that use leverage to manipulate force, levers have been in wide use since antiquity. During the Renaissance period, the world saw an explosion in the number of inventions utilizing levers in their designs. Levers continue to be widely used in modern times.