A white board is similar to a chalk board, only you use nifty colored markers to write instead of chalk. The markers posess a special ink that adheres loosely to the surface of the board, known as dry-erase ink. Once the ink's solvent evaporates, the ink is easily removed from the board with a normal felt eraser. It becomes a fine powder that is much less messy than chalk dust.

Whiteboards are popular with people who are allergic to chalk, and also in computer environments where the much lighter and messier chalkdust gets into equipment. They also provide better contrast than chalk boards if you use high quality markers.

Sometimes someone will accidentally use a permanent marker on a whiteboard. Fortunately, the only difference between dry-erase and permanent marker ink is that the permanent marker ink adheres more strongly. The solvents are so similar that you can erase permanent marker by simply writing over it with a dry-erase marker and then wiping it clean.