Sandpaper is a tool that consists of a sheet of paper covered with sharp particles. It is used to strip, smooth, and polish surfaces, usually wood. The particles are commonly made out of aluminum oxide, garnet, silicon carbide (for hard materials), or other ceramic materials.
To use sandpaper effectively, it is important to start with a low grit and switch to progressively higher grits. "Grit" is a number assigned to each sheet of sandpaper representing its coarseness. Or more precisely, the approximate count of particles per square inch. For example, here are the common names of sandpaper based on the grit:
220-240: Very Fine
280-320: Extra Fine
360-600: Super Fine
See also: tool