Monofilament is a nylon based fishing line that is one of the most popular lines around. Lending to its popularity is the fact it is a relatively inexpensive and versatile line. Monofilament has average toughness, sensitivity and visibility. It is easy to knot to a hook or lure and is “stretchy”. The stretch lends well to applications where you do not want to pull the hook from the mouth of a fish on a hook set or allows for some forgiveness when a fish makes a big run near the boat. The down side of the “stretch” is when left on a spool to long it develops memory and can coil off the spool and become tangled.