Cardboard is a heavy type of paper. It is commonly used because it has properties which show for its stiffness and durability.
Most types of cardboard are recyclable. Boards that are laminates, wax coated, or treated for wet-strength are often more difficult to recycle and care should be taken when using these in biomaterial research as some may not use all natural ingredients, so "Clean cardboard" (i.e.,cardboard that has not been subject to chemical coatings) is safer to use.
Packaging like express boxed are made from cardboard.