Monofilament has ruled the fishing line roost for a half century. It now is getting competition from copolymer lines. For the serious fisherman, however, each line has a place and purpose.
Monofilament is a single strand of nylon or polyethylene. It is the most popular and readily available fishing line in the world. Copolymerization combines two or more nylon or plastic strands into a single line called copolymer.
Monafilament stretches when setting the hook or fighting a fish. Although it floats, it can become waterlogged after extended use.
Copolymer sinks because it is denser. It will stretch, but not as much as monofilament.
The original copolymer was stiff and hard to handle. Adding resin made it softer. The resin, however, gave the line stretch.
Monofilament has a high degree of memory. Strip it from a reel and it will revert to the coil shape of the spool. The results are a loss of casting distance and line snarls.
Copolymer has low memory. It will come off the spool smoother, and cast farther.
Monofilament is a good choice for use with topwater lures. Its stretch gives the angler time to react and set the hook.
Copolymer sworks best for diving crankbaits. Its low stretch is good when quick hook sets are needed to pull fish from heavy cover.