A machine is a device which helps us to do work more quickly. A simple machine is a mechanical device that changes the magnitude or direction of the force. Six simple machines were first identified by Renaissance scientists: lever, pulley, inclined plane, screw, wedge, and wheel and axle. These six simple machines can be combined to form compound machines. A machine enables us to apply less effort for a load greater than the effort or to apply the effort at a convenient point and in the desired direction. A machine enables us to apply less effort for a load greater than the effort or to apply the effort at a convenient point and in the desired direction.