A fishing line is a cord used or made for angling. Fishing line is generally as durable as and comparable to a string. Important parameters of a fishing line are its length, material, and weight (thicker lines are more visible to fish). Factors that may determine what line an angler chooses for a given fishing environment include breaking strength, knot strength, UV resistance, castability, limpness, stretch, abrasion resistance, and visibility. Most modern lines are made from nylon or silk. A fishing line is a cord used or made for angling. Fishing line is generally as durable as and comparable to a string. Important parameters of a fishing line are its length, material, and weight (thicker lines are more visible to fish). Factors that may determine what line an angler chooses for a given fishing environment include breaking strength, knot strength, UV resistance, castability, limpness, stretch, abrasion resistance, and visibility. Most modern lines are made from nylon or silk. Fish are caught with a fishing line by encouraging a fish to bite on a fish hook. A fish hook will pierce the mouthparts of a fish and is normally barbed to make escape less likely. Another method is to use a gorge, which is buried in the bait such that it would be swallowed end first. The tightening of the line would fix it cross-wise in the quarry's stomach or gullet and so the capture would be assured. Fishing with a hook and line is called angling. In addition to the use of the hook and line used to catch a fish, a heavy fish may be landed by using a landing net or a hooked pole called a gaff. Trolling is a technique in which a fishing lure on a line is drawn through the water. Trolling from a moving boat is a technique of big-game fishing and is used to catch large open-water species such as tuna and marlin. Trolling is also a freshwater angling technique often used to catch salmon, northern pike, muskellunge and walleye. This technique allows anglers to cover a large body of water in a short time. Long-line fishing, also known as a trot line is a commercial fishing technique that uses many baited hooks hanging from a single line.