A wedge is a solid triangular shape of any size, usually used to cut or split objects. The history of wedges goes back before human time. Some of the earliest man-made tools were wedges. Even teeth are wedges, splitting food with their points as you exert force from behind. Some household tools take the form of wedges, from kitchen utensils to personal grooming items.
Forks are made up of four small wedges on the end of each tine. When used to poke through food, the slim end of the wedge splits the food apart around the tines due to the force being applied on the handle. Similarly, a nail is a wedge, the slim edge splitting material around it as you apply force to its head with a hammer.
Slicing razors are wedges conventionally used to split hair from skin, with the point of the two incline planes resting where the follicle meets the pore. As you apply force, the two split from each other. Box cutters are razors, and therefore wedges, with an entirely different purpose, as stated in the name. Scissors are another example of slicing wedges. The sharp edge of the wedge splits paper or other substances due to force.
A plow is a pushing wedge. When driven against the snow, it will push snow to one side or the other and out of the way. The wedge's force exerted will always be perpendicular to the direction that the wedge is moving. Shovels work in the same way, the difference being that someone applies the force manually.
A door stop is a commonly used wedge. When placed under a door, the triangular item applies an upward force on the door so that it can no longer move forward to close. No matter what you use the wedge for, the driving principle behind the tool is the same. All types of wedges apply force to a set of incline planes connected on one end. This means there is truly little distinction between the wedges listed here.