A form of joint reinforcement commonly used in miter joints as well as butt joints. The spline itself is usually a thin piece of wood cut so that the grain runs perpendicular to the joint for ultimate strength. The pieces to be joined each receive a groove that will accept the spline. This is a great way to add strength to a joint that normally lacks it. Its also very useful for alignment purposes during complex glueups. Spline slots are usually cut on the tablesaw or with a router.