inside the mouth, and is therefore not the same as angling. Generally, a large treble hook with a heavy sinker is cast into a river containing a large amount of fish (such as salmon) and is quickly jerked and reeled in. Due to the often illegal nature of this method some practitioners have added methods to disguise the practice, such as adding bait or piercing the jerking motion. Sections Traditionally, only a single thread of line is used to connect the hook with the rod and reel. However, most modern angling setups use at least two sections of line joined with a bend knot (such as the famously named fisherman's knot). Occasionally a swivel might be used to join the lines and reduce the bait/lure spinning due to the inherent line twisting from a fixed-spool reel. Backing is the rearmost section of the fishing line and typically used only to "pad up" the spool of the fishing reel, in order to prevent unwanted slippage between the mainline and the (usually metallic and well polished) spool surface, increase the effective radius of the spooled line and hence the retrieval speed (inches per turn), and to shorten the "jump" distance of the line release in spinning reels. The backing can also act as a reserve line in the case of fighting a powerful fish that manages to overpower the drag mechanism of the reel. Mainline is the main section of the fishing line, and the portion that primarily interacts with the rod, line guides and reel. This is the section that handles most of the tensile stress when retrieving the line. Leader is the frontmost section of the fishing line that is attached to the hook/lure, and the portion that most likely will be in actual physical contact with the fish. Many larger, feistier target fish warrants a strong mainline, which might make it too thick to thread through the eye of the hook, thus necessitating a thinner line to "lead" into the hook. Leader lines usually use high-specific strength material with clear colors and water-like refractive indices (thus harder to spot by the fish) such as polyvinylidene fluoride (PVDF, commonly called "fluorocarbon"), or even stainless steel/titanium wires to reduce breakage due to abrasion damage or fish biting. The leader line can also serve as a sacrificial device, as having a leader rated at a designated breaking strength less than that of