Mortise & tenon
A squared tongue in a squared hole — the joint everything else is judged against.
Everything in a timber frame hangs on this one joint: a squared tongue — the tenon — seated in a squared hole — the mortise — and pinned with an oak peg. Cut it a hair tight and it holds for centuries.
How to cut it
lay out knife lines, not pencil — you cut to the line mortise drill, then pare the walls square tenon shoulder first, then cheek to a slip fit peg drawbore: offset the holes 1/16" to pull it home
Why it holds
The peg doesn't carry the load — it locks the tenon against the shoulder. Shrink the wood and the joint only tightens.