The wedge can be thought of as a "portable" (or movable) inclined plane but smaller.

It can also be thought of as 2 inclined planes joined at their bases (particularly the Figure B wedge).

The wedge changes the direction of force.
It converts one vertical force into 2 horizontal forces.

When used as a wood splitter, the wedge (and the wood it is splitting) form what is known as a prismatic joint - a joint that only allows movement along one axis and no rotational motion.

Similar to the inclined plane, the mechanical advantage of the wedge is the "rise over the run" ( or the wedge width divided by the wedge height.)

Examples: knife blade, axe blade, nails, knife, chisel, door stop, wood splitter, wheelchair ramp