This document discusses the different types of simple machines: levers, pulleys, inclined planes, screws, wedges, and wheels and axles. It describes the key components and functions of each machine. First class, second class, and third class levers are explained as well as how their configurations determine mechanical advantage. Pulleys can be fixed, movable, or used in combination. Inclined planes reduce the force needed to overcome gravity. Screws use threads to convert rotational motion to linear motion. Wedges increase force by changing the direction of an input force. Wheels and axles function as a rotating lever with the axle as the fulcrum.