is a form of paperboard
specially manufactured for the production of corrugated fiberboard
. The term encompasses both linerboard and corrugating medium, the two types of paper that make up corrugated board
. Since containerboard is mainly made out of natural unbleached wood fibers it is generally brown, though the shade can vary depending on the type of wood, recycling rate and impurities level. For certain boxes requiring good presentation white bleached pulp or coating is used on the top ply of the paper that goes outside the box.
Production of containerboard is the highest among all kinds of paper in the world, with more than 100 million tons per year. It is mainly manufactured in specialized paper machines out of virgin as well as recycled fibers. Linerboard made of virgin pulp is called kraftliner, whereas recycled linerboard is named testliner. Corrugating medium may likewise be recycled or virgin, the latter being normally called semichemical medium for the pulping process involved in its production.