The fishing line of choice prior to the late 1930s was made of braided Dacron, a synthetic fiber, but this line broke easily and did not stretch much. Braided Dacron is used today mostly by anglers who fish for catfish.
Monofilament line, composed of nylon and introduced in 1939, was a great advance in fishing line. It is made using a complex process that produces a line from a single strand of fiber.
Stren line, a much improved type of monofilament, was introduced to the American fishing public in 1958. It is more resistant to abrasion and has superior knot strength.
Strong heat-resistant fibers, such as Kevlar, Dyneema and Spectra, are braided together to create what can be best described as superior-strength fishing lines. This line's features, such as coloration and knot strength, have improved over time to fulfill an angler's needs.
Flourocarbon fishing line is made from a polymer known as polyvinylidene fluoride and is nearly invisible in the water. It will not absorb water as other lines do and stands up to abrasion and corrosion from forces such as sunlight and chemicals.