Hardboard

Hardboard, also called high-density fibreboard, not to be confused with Hardwood, is a type of fibreboard, which is an engineered wood product. It is similar to particle board and medium-density fibreboard, but is denser and much stronger and harder because it is made out of exploded wood fibres that have been highly compressed.  It differs from particle board in that the bonding of the wood fibres requires no additional materials, although resin is often added. Unlike particle board, it will not split or crack. It is used in construction and furniture.

WIKIPEDIA ENTRY FOR HARDBOARD. 

Hardboard Picture   Hardboard 2 Picture