A wedge is a type of simple machine that is a variation of another simple machine, the inclined plane, which makes it easier to move something to a higher or lower location. However, wedges, made from two inclined planes, are used to cause separations. Shovels, scissors, axes, pick axes, saws and ice picks are all examples of wedges that push things apart.
Other wedges that drive into materials and force them to split are chisels, jackhammers, bulldozers, snow plows, horse plows, airplane wings and bows of boats or ships. Though separation of materials is clearly involved, some wedges, such as staples, push pins, tacks, nails, zippers and doorstops, are ultimately used to hold things together.
When a wedge is narrow, or when it has a sharp point, it is more effective at separating things. For example, narrow fork tines force bits of food apart better than thick tines do. A knife is also a wedge, and sharper knives slice food with less effort. Needles are wedges that come in a variety of sizes and shapes in order to complete different tasks. It is inefficient to use a ballpoint needle, which is rounded, when working with densely woven fabric such as denim. A sharp-point needle pushes through the stiff material better.