Fly fishing is an angling method in which an artificial 'fly' is used to catch fish. The fly is cast using a fly rod, reel, and specialized weighted line. Casting a nearly weightless fly or 'lure' requires casting techniques significantly different from other forms of casting. Fly fishermen use hand tied flies that resemble natural invertebrates or other food organisms, or 'lures' to provoke the fish to strike. Fly fishing can be done in fresh or salt water. North Americans usually distinguish freshwater fishing between cold-water species (trout, salmon, steelhead) and warm-water species, notably bass. In Britain, where natural water temperatures vary less, the distinction is between game fishing for trout or salmon and coarse fishing for other species. Techniques for fly fishing also differ with habitat (lakes and ponds, small streams, large rivers, bays and estuarys and open ocean.)