The Arbor Knot is used to attach the fishing line to the "Arbor" or "Spool Center".The Arbor Knot is really based on a noose knot and, therefore, pulling it tightens it. The Arbor Knot is simple, easily learned and effective.
To Tie an arbor Knot:
Thread the line around reel arbor and tie an overhand knot around the line itself.
Tie a second overhand knot in the tag end. This second knot keeps line from slipping through the first.
Grab on either side of the knots and pull tight. Cut off the excess. Then slide the first overhand knot down the line to snug it around the reel arbor.