Building on what I've written before, it's time to address the fly line. Remember the bull whip and wet towel analogy? Ok then, let's look at a fly line.
Above is a picture of two types of fly line designs. The top one is a weight forward fly line. As you can see the fly line has an initial taper up to a thicker and heavier section. Then, it tapers down to a smaller, level section. All that weight concentrated in the forward section of the line tends to pull the rest of the line with it. Because of this, weight forward lines tend to be a little easier to cast, and are usually a good beginner line. They are also excellent for distance casting and when fighting wind.
The bottom line is a double taper. Double taper lines are the same thickness throughout its length with tapers on either end. Although not as effective for distance casting as a weight forward, double taper lines tend to cast a little smoother and softer. This is good for delicate fly presentations when trying not to spook a fish. Because of the consistent thickness, they make good roll casting lines (we'll get into the different casts later). Since the average cast is typically no more than half the length of your fly line, the end of your line sees little use. Often, when the front and most used part of your fly line is getting old and cracked, the end is still like new. Since a double taper is the same on either end, a budget conscience angler can reverse a double taper line and get twice the life out of it.
The leader is simply an extension of the fly line. Since the fly line is too thick and opaque to tie directly to your fly, you need a go-between. The leader is made out of clear monofilament line. Before you go grab your Berkley Trilene, there's a catch. The leader has to have the continuous taper just like the fly line for it to roll out smoothly and put the fly where you want it to go. Back in the day (and still today) fly fisherman would hand tie their own leaders. The process would entail tying varying thicknesses of monofilament together to create a thicker-to-thinner taper. There are still guys that do this, and it can be very cost effective. Also, tying your own leaders can result in some creative tapers designed to achieve specific casting results. This can give you an advantage depending on the fly and the conditions. the only drawbacks are they can be time consuming to tie, cost quite a bit more initially to get started, and in some cases the multitude of knots can cause trouble with your fly presentation.
Thanking God for modern technology, I embrace the factory-made tapered leader. These can be had for very little money and are tapered without knots - kind of like little fly lines. these are a no-brainer for a beginner. They are sold in standard lengths of 7.5ft and 9 or 10ft - usually matched loosely to the length of your fly rod. The downside is that the taper is always the same. OK, I guess that's a downside...
The end of the leader is called a tippet. No, I don't know why, maybe because it's the tip of the leader. The tippet is the section that is tied directly to the fly. It's ironic, but pound test is not really a consideration for determining the tippet size, but rather it's thickness. Looking back to how a fly line works and how the fly gets casted, you'll understand that the tippet needs to be the thinnest part. Tippets are measures with an odd, "X" system. As you go thinner, the "X" value goes up. So, a 4X tippet is thicker than a 5X or 6X, and so on. Aside from standard lengths, pre-tapered leaders are also designated by their ending tippet size. So for example, if I was shopping for a leader for my small stream rod, I would probably pick up a 7.5ft 5x leader. I will get into matching your tippet to your fly later on, as well as the knots used to tie all the parts together.
Another note on the tippet is how long and when to tie on more. You see, as you tie on each new fly, you are using up more and more of that tippet section. Most tippet sections are around 18 to 24 inches. As you get down to 12-18 inches left of the tippet, it's time to tie on a little more. Fly fisherman will keep spools of tippet "material" handy to replace the constantly dwindling tippet section. Also, if I am going down to a much smaller fly than I had been fishing with then I might need to tie on a smaller diameter tippet section to suit the new fly. OK. I'm running the risk of getting too long winded, so, I'll cover more of this later on as well.
finally let's end with the beginning. A fly line is only about 90ft long. that's not bad for panfish and stream trout, but in cases of bigger waters and larger fish you need more length. Attached between your fly reel and fly line is another type of line called the backing. The backing is usually a flexible, string-like cord that is relatively thin but strong. It has two advantages. First is the obvious - give you more line to work with if a steelhead takes off on a 100 yard run. Second is that it fills up the smaller core of the spool and gives a larger diameter base to wind your fly line on. Since fly lines are plastic, they do have a bit of coil memory when they've been spooled up for a while. Winding backing on a reel before the fly line helps to lessen that effect. 'Nuff said...
So, there's the anatomy of a fly line and it's parts in as brief a description as I feel I can get away with. Next up, we'll talk about fly reels.