A sander is a power tool used to smooth surfaces by abrasion with sandpaper.
Sandpaper and glasspaper are names used for a type of coated abrasive that consists of sheets of paper or cloth with abrasive material glued to one face. Despite the use of the names neither sand nor glass are now used in the manufacture of these products as they have been replaced by other abrasives such as aluminium oxide or silicon carbide.
Sandpaper is produced in a range of grit sizes and is used to remove material from surfaces, either to make them smoother (for example, in painting and wood finishing), to remove a layer of material (such as old paint), or sometimes to make the surface rougher (for example, as a preparation for gluing).
The grit size of sandpaper is inversely related to the particle size. A small number such as 60 or 80 indicates a coarser grit, while a large number such as 1500 indicates a fine grit.
Random Orbital Sander
A hand-held sander that vibrates in small circles, or "orbits." The sanding disk spinning while moving simultaneously in small ellipses causes the orbital action that it is known for. Mostly used for fine sanding or where little material needs to be removed.
A belt sander or strip sander is a sander used in shaping and finishing wood and other materials. An electric motor turns a pair of drums on which a continuous loop of sandpaper is mounted. Belt sanders may be handheld and moved over the material, or stationary (fixed), where the sander remains stationary and material is moved along the sanding belt.