A firm rubber surface used to protect tables and other surfaces from damaging cut marks from Stanley Knifes and Scapels. A cutting board is primarily used when cutting works on paper, it is used a lot for scrap booking and other papercrafts as well as the art of collage.
The surface texture of a cutting mat will somewhat grip paper holding it in place as you cut. A good cutting mat will also have a printed grid on it, which allows you to accurately measure as you cut.
You can purchase cutting mats from any good art supply store or framing supply store.
TIP: When cutting on a cutting board, be sure to use only a metal ruler as your straight edge! The knife will damage a wooden or metal one.