Simple machines are devices that change either the direction or the magnitude of a force, making it easier to do work. The classic six are the inclined plane, wedge, screw, lever, pulley, and wheel-and-axle. Key ideas

• They typically have few moving parts and enable tasks with less effort, often by trading force for distance.
• Mechanical advantage is the ratio of output force to input force; increasing advantage usually means moving the load farther or through a longer path.

Quick overview of each type

• Inclined plane: A flat surface set at an angle, reducing the required lifting force by allowing the load to be raised more gradually.
• Lever: A rigid bar that pivots around a fulcrum; effort times distance from the fulcrum balances with load times its distance.
• Wheel and axle: A wheel attached to a smaller axle; rotating the wheel moves a heavier load via a longer distance but with less force.
• Pulley: A grooved wheel with a rope or belt; can change the direction of effort and, with multiple pulleys, increase force advantage.
• Screw: An inclined plane wrapped around a cylinder; converts rotational motion into linear motion and can hold things together or lift loads.
• Wedge: A pair of inclined planes back-to-back; used to split or fasten by applying force in a direction that drives the wedges apart.

Common applications

• Lifting and lowering loads with less input force (ramps, ramps on staircases, wedges for splitting).
• Lifting and moving heavy objects with pulleys or block-and-tackle systems.
• Fastening objects with screws or bolts.
• Holding objects in place with wedges and screws.
• Everyday tools and machines often combine several simple machines to perform more complex tasks efficiently.

If you’d like, specify a particular context (e.g., physics class, engineering design, or a practical task), and the explanation can be tailored with examples, diagrams, and a quick derivation of mechanical advantage for the relevant device.