A lever is a simple machine consisting of a rigid bar that pivots around a fixed point called the fulcrum. In a first-class lever, the fulcrum is between the effort and the load, such as in a seesaw. In a second-class lever, the load is between the fulcrum and the effort, like in a wheelbarrow. In a third-class lever, the effort is between the fulcrum and the load, as seen in tweezers. Each type leverages the position of the fulcrum to make lifting or moving objects easier.