A wedge utilizes a principle known as mechanical advantage in order to reduce the force needed to lift or separate an object. When driven under load, wedges function by transferring the direction of force applied.
A wedge is comprised of two inclined planes that taper to a point. A wedge provides a level of mechanical advantage that is equal to its length divided by the base. Wedges that are long and thin can be driven with less overall force, but they must be moved a greater distance in order to do as much work as a short and thick wedge. Wedges with a curved surface are designed to be moved, while those comprised of a flat inclined plane must remain in place in order to function.
Wedges are one of six simple machines, which are devices which are used to reduce the amount of force needed to do work. Wedges can be used as either a standalone device, such as a doorstop or an axe, or they may be used as components within more sophisticated devices that utilize multiple simple machines working in concert in order to make work easier. Knives, chisels and even piercing devices, such as nails, are all examples of a wedge.