Terms of the Trade: What Is a Mortise and Tenon Joint?

A pair of hands inserting a mortise and tenon joint around woodworking tools.

The mortise and tenon joint has been around for as long as people have been trying to connect two pieces of wood at a 90 degree angle. (Some say it dates back almost 7,000 years.) The "mortise" portion is a square or rectangular hole in which the "tenon," a projection at the end of a separate piece of wood, is inserted. There are various kinds of mortise and tenon joints, but they all are known for being strong, and are usually glued or wedged into place.