A wedge is a simple machine used to separate two objects, or portions of objects, through the application of force. A wedge is made up of two inclined planes. These planes meet and form a sharp edge. This edge can split things apart. Wedges are used as either separating or holding devices. There are two major differences between inclined planes and wedges. First, in use, an inclined plane remains stationary while the wedge moves. Second, the effort force is applied parallel to the slope of an inclined plane, while the effort force is applied to the vertical edge (height) of the wedge. Force multiplication varies inversely with the size of the wedge angle; a sharp wedge ( small inclined angle ) yields a large force.

Wedges are used as either separating or holding devices. A wedge can either be composed of one or two inclined planes. A double wedge can be thought of as two inclined planes joined together with their sloping surfaces outward.