A figure eight knot
is made at the end of a single rope
, either to provide a stopgap
to prevent the end from slipping through a fitting, or to provide a loop in the rope to which things may be attached.
To make a figure eight knot, hold the end of a rope pointing away from you. Fold the end over and back towards you to create a loop. If you were to push the end forward again, under the straight part, and *up* through that loop, you would have a half hitch, the simplest knot possible. However, half hitches weaken a rope under strain because of their asymmetry. Instead, fold the end back towards you, under the straight part and up again on the left and *down* through the loop. Notice the symmetry; it's a beautiful knot. It also weakens a rope under strain much less than a half hitch. When you want to undo it, just push one end into its loop and the knot will soften and undo.
A figure eight is the safe and proper way to tie yourself into a climbing harness, or to attach a rope to an anchor. Make a figure eight with about eighteen inches of tail left loose. Pass the tail through the loops of your harness or around the anchor carabiner. Now pass the end back through the knot *in the opposite direction*, following the "incoming" rope precisely through the two loops. You should now have a *double* figure eight, with a bight on one side, passing through your harness or anchor, and the long end facing away from you with the remaining tail parallel to it. Tie off the tail with half hitches to prevent flapping or bouncing from loosening the knot, and you're set.