Monofilament fishing line is fishing line made from a single fiber of plastic material, as opposed to multifilament or braided fishing lines constructed from multiple strands of fibers. Most fishing lines are now nylon monofilament because they are cheap to manufacture and can be produced in a range of diameters which have different tensile strengths. Monofilament line is also available in different colors, such as clear, white, green, blue, red, and fluorescent.

A fishing line is any flexible, high-tensile cord used in angling to tether and pull in fish, in conjunction with at least one hook. Fishing lines are usually pulled by and stored in a reel, but can also be retrieved by hand, with a fixed attachment to the end of a rod, or via a motorized trolling outrigger.