There are six types of simple machines:
Wheel & axle—Can serve as speed multipliers or force multipliers and reduce friction, so less force is needed
Pulley—Made from a wheel with a divot where a rope can rest. When a force pulls on the rope, it turns the wheel and redirects the force to more easily lift or lower heavy objects on the other end up
Lever—The fulcrum, or pivot point, transfers force applied to one end of a bar to the other end; where you put the fulcrum makes it easier to lift a load or apply force
Wedge—Force is applied to the thick end and get directed down to the point and out into an object, splitting it apart or holding it in place
Inclined plane—Pushing a load upslope takes less energy than lifting straight up against gravity; at the top, potential energy can be converted into kinetic energy to bring a load back down
Screw—Actually an inclined plane wrapped around a cylinder! Redirects force up and down to bring surfaces tight together or push them apart