A wedge is really an inclined plane turned on its side. But instead of helping you move things to a higher level, a wedge helps you push things apart. The blades of a knife or a shovel are both wedges. A wedge can also be round, like the tip of a nail, or the tines on your fork. Basically, the wedge works just like a ramp: The narrower the wedge (or the sharper the point of a wedge), the easier it is drive it in and push things apart. But here's the trade-off: To split something apart really wide, you have to push the wedge a long distance.