The document defines and describes six simple machines: pulley, lever, wheel and axle, screw, wedge, and inclined plane. It notes that a pulley uses a grooved wheel and rope to raise, lower, or move loads in the opposite direction of the applied force. A lever is a stiff bar that lifts or moves loads using a fulcrum as a pivot point, requiring less force over longer lengths. A wheel and axle combines a wheel that turns on a central rod or post, also allowing loads to be moved with less force when the wheel is large.