Sand paper is a form of paper where an abrasive material has been adhered to its surface, it is part of the "coated abrasives" family of abrasive products. 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. Shark skin has been used as a substitute sandpaper.

The first recorded instance of sandpaper was in 13th century China when crushed shells, seeds, and sand were bonded to parchment using natural gum.

Sandpaper has occasionally been used as a surface for painting, as by Joan Miro.

Sandpaper was even used as a musical instrument, in Leroy Anderson's Sandpaper Ballet.

Sandpaper was patented in the United States on June 14 1834 by Isaac Fischer, Jr., of Springfield, Vermont.