Half lap

Two members each notched to half their depth, lapped over each other so the faces end up flush. Where they cross, you drive a peg straight through both.

How to cut it

half depth  mark both faces with a gauge
shoulders   saw to the line on both pieces
cheek       chisel out the waste to a flat bed
peg         through the lap, or let the joint bind

Where it lives

Knee braces, crossing ties, and anywhere two timbers pass over each other without stacking height.