The mortise and tenon joint has been used for thousands of years by woodworkers around the world to join pieces of wood, mainly when the adjoining pieces connect at an angle of 90°. In its basic form it is both simple and strong. Although there are many joint variations, the basic mortise and tenon comprises two components: the mortise hole and the tenon. The tenon, formed on the end of a member generally referred to as a rail, is inserted into a square or rectangular hole cut into the corresponding member. The tenon is cut to fit the mortise hole exactly and usually has shoulders that seat when the joint fully enters the mortise hole. The joint may be glued, pinned, or wedged to lock it in place.

This joint is also used with other materials. For example, it is a traditional method for stonemasons and blacksmiths.

A mortise is a cavity cut into a timber to receive a tenon. There are several kinds of mortises,:

A tenon is a projection on the end of a timber for insertion into a mortise. Usually the tenon is taller than it is wide.

Paul Sellers was born in 1950 and apprenticed in the UK in 1965 . He moved to the US in 1984 and quickly became noted for his ability in traditional woodworking. He has taught thousands of people in the craft of woodworking. He teaches in the USA and the UK for the New Legacy School of Woodworking . Sellers is author to Working Wood which was published in 2011.