Plywood is constructed by bonding together an odd number of wood veneers with the grain of each layer being perpendicular to each other. Most plywoods are homogeneous in structure and due to their construction, allow for stronger panels that are more stable in both directions. Plywood can be made from a variety of wood species.
Generally, plywood can be bonded in one of two ways, either using a urea formaldehyde (UF) for interior applications or phenol formaldehyde (PF) or similar resin for exterior applications.