What it does: Its primary use is to attach fishing line to the arbor/spool of a fishing reel.
Why is it useful: It secures the fishing line on your reel arbor/spool
How to tie it:
1. An arbor knot is tied by first passing the line around the reel arbor.
2. The tag end is then tied in an overhand knot around the running line.
3. Finally, an overhand knot is tied in the tag end. When tightened, the overhand knot in the tag end jams against the overhand knot tied around the running line