Certain hardwood is a term used to describe a variety of wood types that are known for their strength and durability. The most common types of certain hardwood are OAK, TEAK, and redoak. OAK is a type of hardwood that is commonly used in furniture and flooring due to its strength and durability. TEAK is a tropical hardwood that is often used in outdoor furniture and boatbuilding due to its resistance to rot and decay. Redoak is a type of hardwood that is known for its reddish-brown color and is often used in cabinetry and furniture.