Biscuits. Not that kind, silly goose. The woodworking kind. A biscuit jointer, or sometimes called a plate jointer, is a machine that cuts a slot to receive these biscuits. A little glue, baboom, you’re in business. These do reinforce the joint to some extent, but they’re mostly for alignment. The glue is definitely doing the majority of the work. If ya didn’t know now ya know. | Justin Metzler