Fly Fishing Leaders and Tippet:
First question, just what are leaders and tippet? A tippet material is a particular gauge monofilament or flurocarbon line which should be attached to the end of your tapered leader which could be a  monofilament leader or fluorocarbon leaders then tied to your fly. Tapered leader   material are availably in Flurocarbon, Monofilament/ Nylon leaders. The leader and tippet is made from monofilament or flurocarbon, fluorocarbon giving the greatest abrasion resistance and monofilament giving a higher knot strength, normally the littlest gauge line on your rig and is nearly invisible to the fish. Adjust your tapered leader weight to the size of the fly. Normally the tippet section is 2 to 4 feet in length and matches, or is smaller than, the diameter of the tapered leader's tip. The biggest advantage to using tippet is that it extends the life of the leader. Leaders can be expensive and if you change flies often, little by little the taper of the leader is cut away. By tying on tippet, you can avoid losing taper. A tippet ring can also be used. The fly is tied to the end of the tippet material. What type of fish you are fly fishing for determines the type and size of the fly. Flies come in all different shapes and sizes that range from very small #28 dry flies to large #2. There are still larger flies, but they are categorized on a different scale. To help determine what gauge leader and tippet to use with a particular size fly, many leader manufacturers insert a small chart inside their packaging. The leader is attached to the end of the colorful fly line and gives the fisherman a virtually transparent connection between the line and the fly. Commercially bought leaders come in a variety of lengths with 7.5 to 9 feet being most common. Most leaders are tapered monofilament also known as nylon leaders, meaning they are a larger diameter at the butt section, which attaches to the fly line, and a smaller diameter at the tip, where the tippet or fly is tied. During the cast, the taper allows the leader to shoot through the air more efficiently and rest more softly on the surface of the water, the butt section is the only section that is directly joined to the fly line. The butt section is the thickest portion of the leader and is usually made from stiff line that is about the same stiffness as the fly line. Turnover power increases as the length of the butt section increases, while too short of a butt section in relation to the midsection and tippet may not provide proper turnover power for heavy flies.
Euro nymph leader are specialy designed for Euro nymphing if using a 10' rod (3m), the standard length for euro nymphing, a classic uero nymph leader would be 20' including the tippet. So you would have about 15' (4.50m) without the tippet, which would allow fishing properly until roughly 7 to 8m. The angle between the rod and the line is by then around 90 degrees, as recommended. Nymphing rigs can be made up of different fly combinations with diferant lengths of tippet.

 Leaders come in different weights and strengths. The correct leader and tippet weight is primarily determined by the size of the fly. Fluorocarbon is denser than monofilament, making it more abrasion resistant, Abrasion resistance is important when nymphing or fishing saltwater. Monofilament is nearly the same density as water, making it neutral-buoyant so better for fishing dry flies. This is the opposite of fluorocarbon, which is denser than both, allowing it to sink. The average fly fisherman use mono for most of their fly fishing because of the extra stretch when fighting fish  note monofilament has a higher knot strength compared to flurocarbon. But when I am nymphing I use fluorocarbon because it doesn't stretch thereby giving me greater contact to detect the take and is abrasion risistant. Fluorocarbon is also usefull in saltwater inviroments as it has greater abrasion resistance giving a little extra protection against coral, rocks and toothy criters. Saltwater flats fishing is the only time I use fluorocarbon leaders. Chooseing the right knot for knot strength compared other knots is important when you are fly fishing. You can find many videos and articles on knot strength online which is fine as a reference but you have to be able to tie them perfectly otherwise you just won't achieve the high knot strength. I would do the research choose the knots that you think will give you the best knot strength, then practice, practice and practice until  you get the consistant high knot strength you desire. Remember poor knot strength equals lost fish! Flurocarbon knot strength compared to Monofilament is important to note. When it comes to knotability, the monofilament is superior by a wide margin since it is more flexible than fluorocarbon. Leader tippet are essential components in your fishing rig and a tippet ring are very usefull. 
Many companies like Scientific Anglers and Rio make great leaders and tippet like absolute fluorocarbon and fluro flex. Absolute fluorocarbon is a great material for saltwater flats fishing, leaders and tippet with great knot strength but you will find other brands just as good without the premium price.


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