Nylon was invented in 1938 by DuPont; nylon fishing line followed soon after in 1939. It did not have a large following at first, as braided Dacron line was more popular.
When DuPont placed a nylon line called Stren on the market, nylon line began to dominate sales. Stren was thinner than other lines, allowing fishermen to use it on many types of reels.
Monofilament nylon lines make up two-thirds of all fishing lines bought by anglers. Name brands are more reliable than the cheaper kinds, having more strength and stretching less.
To form nylon line, molten plastic is made into a single strand through a very inexpensive extrusion process. This is why it is cheaper than other types such as fluorocarbon and braided lines.
Pros and cons
Monofilament nylon fishing line casts smoothly off a reel and cuts without much effort. However, it stretches more easily, absorbs water and breaks under stress more rapidly than other lines.