Monofilament fishing lines are strong, translucent fishing lines used in freshwater fishing. However, their ability to absorb water and thus weaken knots makes it inadequate for deepwater fishing.
Monofilament line is popular because of its strength and cheapness, and due its availability in a number of different pound test strengths. In addition, the fact that it's translucent is a benefit, as it is almost invisible to fish.
Monofilament line can be made from a variety of material types, including nylon and stren.
Monofilament lines stretch, which can be a good thing, as it resists breakage, but it can also make it harder to set the hook.
Improperly discarded monofilament lines are an environmental concern, as it can entangle fish, birds and even swimmers. Because of these issues, many states are implementing monofilament recovery and recycling programs.