Fly fishing is a distinct and ancient angling method, most renowned as a method for catching trout and salmon, but employed today for a wide variety of species including pike, bass, panfish, grayling and carp, as well as marine species, such as redfish, snook, tarpon, bonefish and striped bass. There are many reports of fly anglers taking unintended species such as chub, bream and rudd while fishing for 'main target' species such as trout. There is a growing population of anglers whose aim is to catch as many different species as possible with the fly.

Fly fishing can be done in fresh or salt water. Freshwater fishing is often divided into coldwater (trout, salmon, steelhead), coolwater (pike, perch, walleye) and warmwater (bass, chub, catfish) fishing. The techniques for freshwater fly fishing also differ in lakes, streams and rivers.

In fly fishing, fish are caught by using artificial flies that are cast with a fly rod and a fly line. The fly line (today, almost always coated with plastic) is heavy enough in order to send the fly to the target. This is one of the main differences between spinner and bait rods, which use heavy weight on the line to cast lures, bait, etc. Artificial flies can vary dramatically in all morphological characteristics (size, weight, colour, etc.).

Artificial flies are created by tying hair, fur, feathers, or other materials, both natural and synthetic, onto a hook with thread. The first flies were tied with natural materials, but synthetic materials are now very popular and prevalent. The flies are tied in sizes, colours and patterns to match local terrestrial and aquatic insects, baitfish, or other prey attractive to the target fish species.