Corrugated cardboard or fiberboard is made of two components: linerboard and medium. The medium is the wavy fluted paper. The linerboard is the flat facing that adheres to and protects the medium.

Single wall corrugated fiberboard is composed of two layers of linerboard sandwiching one layer of medium.

Double wall corrugated fiber board is composed of three layers of linerboard sandwiching two layer of medium.