Sandpaper is a tool made of paper or cloth covered with rough, gritty particles that you rub against wood, metal, or other surfaces to make them smoother. The tiny grains of sand or similar materials work like countless miniature chisels, scraping away imperfections bit by bit.

If you've ever run your hand along a wooden bookshelf and felt splinters or rough spots, sandpaper is what woodworkers use to eliminate those problems. They rub it back and forth across the wood until the surface becomes smooth enough to paint or seal. Different grades of sandpaper exist: coarse sandpaper removes material quickly for heavy jobs, while fine sandpaper creates an ultra-smooth finish for delicate work.

The word also appears in descriptions of rough textures. When someone's hands feel like sandpaper after working outside all day, their skin has become dry and scratchy. A cat's tongue feels like sandpaper because it's covered with tiny backward-facing hooks that help the cat groom itself.

Using sandpaper well requires patience. Rubbing too hard or too fast can damage what you're working on. Done properly, though, sandpaper transforms something rough and unfinished into something smooth and ready for the next step.