Fly fishing line and backing, from brands like RIO and Scientific Anglers, are integral components of a fly angler's setup. The fly line is the main connection between the rod and the fly, crucial for accurate casting and presentation. It comes in various tapers, weights, and types such as floating, sinking, or intermediate lines, each tailored to specific fishing scenarios. Weight-forward lines are common for their versatility in delivering flies with precision.

Backing is a supplementary line attached to the reel, providing extra line capacity and ensuring a fish doesn't strip all the fly line during a powerful run. It's typically made of strong, low-stretch material like Dacron or braided Spectra. When hooked into a large fish or encountering long runs, backing plays a vital role in preventing line breakage and securing a successful catch. Properly matching and maintaining fly line and backing enhance an angler's chances of a rewarding fly fishing experience.