A mortise and tenon joint is one in which the rectangular end (the tenon) of one piece fits into a rectangular hole (the mortise) of the same size, in the other piece. Mortise and tenon jonts are made in a number of different types.. The blind mortise and tenon is the most common. It is used extensively in cabinetmaking for joining rails to legs or stiles, and in many other constructions well. When properly designed, proportioned, and well made, mortise and tenon joints are strong and neat in appearance.