There are various ways to present a fly. The most common is with a floating line on the surface of water. Rods enable you to get the line and the fly to the fish. Fly rods are usually 6-14 feet in length and made of Graphite, Bamboo or Fiberglass. They come in many different styles for the different taste of the person using it.
Different fish require different rods.
The reel serves many purposes. Reels come in many different sizes depending on the species of fish and the rod that you are using. Most new reels are made from 1 piece of bar stock aluminum and machined to perfection. There are also reels made from a cast mold, these reels work well and are usually cheaper in price. Line is used to get the fly where it needs to be and enables you to bring the fish in.