The Level Taper (L)
Level taper fly lines are the easiest to understand and the least used in the sport of fly fishing. A fly line that has a level taper, in essence, has no taper! You see, a level taper fly line is of uniform weight and width for its entire length.
The Double Taper (DT)
A double taper fly line is a fly line that is heavy and thicker middle section, and then gradually loses both width and weight the closer it gets to the end of the fly line. What is important to remember about double taper fly line is that it is balanced - both ends of the fly line weigh the same and each end gradually increases in width and weight the closer it gets to the middle section of the fly line at an equal rate.
Weight Forward Taper (WF)
The weight forward taper fly line is the most popular fly line on the market today. A fly line that has a weight forward taper has extra weight and width built into the first 30 feet of the fly line, although some specialized lines extend or shorten this taper. The rest of the fly line will then be level, of equal weight and width for the remainder of the fly lines length. The advantages of a weight forward fly line include longer casts, the casting of larger flies and more effective casts in windy conditions.
Shooting Taper (ST)
Shooting taper fly lines were initially designed for fly casting distance tournaments. Which should tell you about their function. A shooting taper fly line is a specialized fly line that is heavily weighted on the first 20 feet of fly line. Then, the remainder of the fly line is of a uniform thickness and weight, but is much thinner than a traditional weight-forward fly line.
Fly Line Density
The density of a fly line refers to whether the fly line floats or sinks and, if it sinks, how the fly line is designed to sink
The floating fly line does just what the name suggests - the fly line floats for its entire length. Floating fly lines are both the easiest to cast as well as the most popular type of fly line
Sinking Tip Line
The sink-tip fly line is another popular fly line. A sink-tip fly line is a fly line that sinks for the first 10-30 feet. The remainder of the fly line will continue to float
Intermediate Sinking Line
An intermediate sinking fly line is a fly line that will sink entirely, but at a relatively slow rate. Intermediate sinking fly lines are ideal where you want to submerge your fly just a little bit, with the fly line very slowly settling down into the water
A sinking fly line is a fly line that will sink relatively quickly at a uniform rate. The actual sink rate of a sinking fly line will vary considerably and will be listed on the box. A sinking fly line can sink anywhere from 2 to 10 inches per second
Leader and Tippet
The leader and the tippet are the two terminal parts of the setup before your fly. The leader is attached to the front end of the fly line and the tippet is attached to that. Your fly is tied to the tippet. The leader is a tapered piece of line - it's thicker towards the fly line and thinner towards the tippet and fly.