NAIL KNOT
the knot used to attach a leader to a fly line or to the butt section (q.v.) which rolls out well when casting. Can also be used or to attach line to hooks, swivels, snaps and lures where a double loop through the eye provides a cushion for extra knot strength. A nail or needle can be used to wrap the line around to facilitate tying this knot. Various websites have animated steps showing how to tie this knot