Difficulty: Moderately Easy
Instructions
Sometimes when climbing you'll find you need to tie an overhand knot somewhere in the middle of the rope. This is called an overhand on a bight. A knot on a bight simply means you bend the rope and tie both strands of the rope in the regular fashion. An overhand on a bight is often used to haul bags or gear up a route.
eHow Article: How to Tie an Overhand Knot on a Bight