Sandpaper is a form of paper where an abrasive material has been adhered to its surface. It is used to remove small amounts of material from surfaces, either to make them smoother (painting and lacquering), to remove a layer of material (e.g. old paint), or sometimes to make the surface rougher (e.g. as a preparation to glueing).

There are countless varieties of sandpaper, with variations in the paper, the glue (water-resistant or water soluble), the material for the abrading particles (glass powder, sharp sand, corundum, carborundum, diamond), the grain size, the distance between the particles, and the shape of the sheet.