abrasive material used for smoothing softer materials

Sandpaper is a piece of paper with an abrasive glued to it. Sandpapers come in various types. Some are very rough, while others are very smooth. They are used to clean wood and metal and make them smooth. Some sandpaper is made to go on a machine that rubs very fast, while other sandpaper is used by hand.

Grinding blocks and a sheet of sandpaper