Plywood is one of the most commonly used wood products available today.  It is a type of engineered wood manufactured from thin sheets of cross-laminated veneer and bonded together. The layers are glued together, each with its grain at right angles to adjacent layers for greater strength. There are usually an odd number (3, 5, 7)of plies, so that the grain on the outside plies runs in the same direction. The plies are bonded under heat and pressure with strong adhesives, usually phenol formaldehyde resin. It is extremely versatile, strong, durable, and comes in several grades and thicknesses.