The One-Handed Clove Hitch might be the single most useful knot for trad climbing. With it you can quickly and easily secure yourself to any anchor point. It is incredibly adjustable as well. Learn it well, and you won't know how you ever got by without it.

How to tie:
      First, clip the rope once into a carabiner. The rope should pass from the trailing end up through the back of the carabiner and out the front to your harness. If not, that is sometimes ok, but be sure you know which side is in the back. Turn your hand thumb down and reach across the front part of the rope and grab the trailing end. Pull that end across the front part, twist your hand thumb upwards again, and clip the rope into the carabiner a second time. Pull tight, and you have a clove hitch! This is a really hard knot to describe in words, so definitely check out the video below for tips (video coming soon!).