A cutting mat is a firm rubber surface used to protect tables and other surfaces from damaging cut marks from Stanley Knifes and Scalpels.  cutting mat is also often called a cutting board. 

A cutting mat is primarily used when cutting works on paper, it is used a lot for scrap booking and other paper crafts as well as the art of collage this is because cutting with a blade or scalpel gives a far greater degree of accuracy than cutting with scissors especially if you are cutting cardboard such as Bristol Board or Mat Board.

The surface of a cutting mat has a slight texture that helps to grip the 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 and/or cut square edges.

You can purchase cutting mats from any good art supply store, framing supply store or any stores specializing in drafting equipment.

CUTTING MAT TIP: When cutting on a cutting mat, be sure to use only a metal ruler as your straight edge! The knife will quickly damage a wooden or metal one thus ruining the ruler and the straight edge it provides.