There are many, many huge advantages to having good backing on your fly fishing reel. Fly reel backing is usually constructed with dacron or braided polyester, and it should be the very first layer of line you put on your fly reel. Purchase in 50 to 300 yard spools. For your general fly fishing for trout and small freshwater species 50 meters of backing is ample. When you are spooling up for saltwater species especially pelagics you should aim for 200 to 300 meters depending on the size of your reel. While dacrod is fine for smaller species like trout I would suggest a quality thin backing of about 30lb for the salt. The finer your backing the more you will fit on your reel. Now lets talk Fly Line. Fly Line taper is one of those mysterious subjects that something few understand despite being quite simple. So, lets' begin with a very simple question...what the heck is a fly line taper? A fly line taper is a small adjustment made by the manufacturer of the fly line to the fly line itself. This generally involves making parts of the line thicker in spots, heavier in spots, thinner in other spots, lighter in other spots. These adjustments to the fly line are done to give the angler better control of the line which, in theory, means improved casting. Ultimately, whenever someone mentions "fly line taper" - think "adjustments to fly line." Because an adjustment to the fly line is all a fly line taper is. So, why is fly line taper important? The taper of fly line plays an important role in how accurate an angler casts. This is rather important, obviously, in determining whether you catch any fish.The Types of Fly Line Taper Well, now that you know what a fly line taper, the next step is to understand the different types of fly line tapers available. There is quite a few of them, and more seem to be invented everyday, or at least every year. Yet, the general angler who chases trout, panfish and bass need only concern themselves with the following four types of fly line tapers. WF - The Weight-Forward Taper This is the "standard" taper for trout fishing. A Weight Forward Taper (abbreviation of WF on fly line boxes) is a fly line that has additional weight and thickness added to it in the first 10 yards of fly line. The remainder of the fly line is then of uniform thickness and weight. The purpose of the weight-forward taper is to provide additional "heft" to the fly line. This additional "heft" allows the angler to make casting easier, especially on windy days. Since additional weight is on the front of the fly line, longer casts can also be made too. Finally, the extra weight on the end of the fly line helps larger flies turn over properly, thus landing on the water with proper presentation. DT - The Double Taper The Double Taper (abbreviation DT) is a fine fly line taper for trout fishing, unless you need to make long casts or it's windy. On a DT fly line the first fifteen feet of the fly line gradually widen in diameter. The next 60 feet of the fly line remains a constant weight and width. The final 15 feet of the fly line then gradually loses width and weight at exactly the same rate as was gained on the front of the fly line. One benefit of this type of taper is that it can be reversed as both ends of the fly line are equal. So, why would a angler want to use double-taper fly line? Simple, the lighter front-end weight of the fly line allows for a "lighter touch" when casting and presenting the fly. However, the trade off is that it is more difficult to cast in windy conditions and shorter casts are more difficult to control. In short, both the DT and WF tapers are perfect for trout fishing. Choose the taper, at the end of the day, that works well for the type of fishing you will do. The Shooting-Taper (ST) fly line is essentially a Weight-Forward fly line on steroids. The first 20 feet of the fly line is heavily weighted - far more so than a WF fly line. The remaining fly line is then of uniform width and weight, but is especially narrow. The purpose of a ST fly line is simple - tournament casting - where anglers try to cast the fly as far as possible. Few anglers ever use this type of line while fly fishing since the hassles of the line outweigh its long casting benefits. Unless you are an expert angler, there is no reason to use, or even own, a ST fly line. That is, unless you plan on tournament casting or just want to see how it works. Understanding Fly Line Density Fly line density is a very simple term to grasp, actually. All fly line density means is whether the fly line float, sinks, or just partially sinks. Simple. A floating fly line is by far the most popular and versatile fly line. A floating fly line, as the name suggests, floats completely. It does not sink unless the line is weighed down. If an angler can own only one fly line, make triply sure that it is a floating one. Through the addition of weights an angler can always make a floating line a "sink-tip" line. By contrast, a sinking fly line sinks - completely. How fast it sinks (known as it sink rate) is variable - depending on the sink rate of the line. Some lines sink very fast, others very slow. The point, though, is the the entire fly line will sink - and will sink at a uniform rate. As a sidenote, the "sink rate" of a fly line will be noted somewhere on the fly box, measured in "fps" - feet per second. Sinking fly lines are great for big water fishing, particularly lakes and saltwater. They have limited utility in an average river and are rarely used. Since sinking fly lines have limited utility for trout fishing, but because floating fly lines don't always do the job of pulling down nymphs into the depths of the river quick enough, a hybrid was designed - the "Sink-Tip" fly line. On a sink-tip fly line, only the first 10 to 30 feet of the fly line sinks. The remainder of the line floats. The purpose of this line is to allow for fishing of nymphs and streamers in the depths of rivers where the current is moderately fast. The heavy line, especially if used with some additional weights, can bring a nymph down to depth quickly and keep it there. For trout fishing, the angler will want to first get a floating fly line. Later, money and desire found, a sink-tip fly line can also be purchased for those "special situations" where the line really is needed.