Simple Machines are devices that affect the force or effort needed to do a certain amount of work. Machines can make a tough job seem easier by enabling a person to apply less force or to apply force in a direction that is easier to manipulate. There are four types of simple machines: the lever, the pulley, the inclined plane, and the wheel and axle. Each machine affects the direction or the amount of effort needed to do work. Most mechanical machines, such as automobiles or power tools, are complex machines composed of many parts. However, no matter how complicated a machine is, it is composed of some combination of the four simple machines.