Euro nymphing is the synthesis of diverse approaches to nymph fishing that were developed in European geographical areas. These techniques evolved first in the competition arena. The aim was to present the nymphs as close as possible to the bottom, letting them sink fast so they could be in the feeding zone for the entire drift. As well, this type of rig is able to dramatically reduce the dragging to almost none, so the angler is more in contact and 'feels' the nymphs at the end of the leader. To achieve this, in Euro Nymphing the leader's length can be twice or more the length of the rod. No fly line is used to propel the flies, the casts leverage on the weight of the flies, the leader and rod swing weight.
Even if the technique lacks the elegance and casting esthetic of the classic fly-fishing style, Euro Nymphing is a very effective way of reaching the main foraging areas, where active fish station the most of the time.

The Leader:
Premise that there is a plethora of flavors in how the leaders are built and the specific lengths of each segment, below two examples of Euro Nymphing rigs:

The length and diameter of each segment can be adapted to fit the specific river, flies' weight and depth at which one is fishing. Personally I prefer to keep it as simple as possible, Nonetheless, the market now offers more disparate solutions: thin specific shorter fly lines, tapered leaders, euro nymphing reels and alike.
One thing that cannot be compromised on, is the rod. Lighter rods in the correct length, that is 10 to 11 foot canes for a line weight 2 to 4 and with a parabolic or semi-parabolic action have definitely an edge.

A thin tippet offers less friction during the sinking phase and allows the use of smaller flies. The tippets carry (where fishing rules allows it) two to three flies, which speeds up the sinking and extends the search zone. The fly at the end of the tippet (the point fly) is normally the heaviest, the second fly is called the dropper. It is very important to gauge the weight of the flies in relation to the current and the depth at which we are fishing. A too heavy rig will keep on snagging, a too light one will not reach the feeding zone.

The leader below is my actual favorite for fishing the alpine mountain streams.

FISHING ACTION:
As the rig will only allow short casts, the angler has to get closer to the trout. Euro nymphing is ideal on alpine stream with a width between 5 and 20 meter. Here the faster sinking rate and the almost virtual absence of dragging will allow you to explore every nook and cranny of the bottom, where trout feed most of the time. Without the counterweight of the fly-line, the weighted nymphs will keep tension on the thin line and the anglers will feel (almost) any bite. The nymph has to drift as naturally as possible, so that it will drift in front of the fish. The fast reaction of the angler is often key in setting the hook before the fish realizes the deception. This type of fishing is not about elegant casting or fishing the hatch, but it does what it required to be able to fish the bottom. It can be real fun to be search and guess where the trout ares stationing, and it helps to develop a good 'sense de l'eau' for the trout feeding preferred spots. The chances it offers, by placing the flies deep in each possible trout feeding spot and keep them in the hot area with minimized or null dragging, are also remarkable in terms of caught fish. When fish rise, it is possible to mount a dry fly as dropper or simply to remove the long leader and replace it in a minute with a classic leader. All in all, Euro nymphing is another tool in the belt that is worth to try.

TOP NOTCH FLIES FOR EURO NYMPHING

The pheasent CDC:

EUREKA, caddisless sedge pupa:

P & P Pheasent and partridge:

Perdigon:

Fat perdigon: Dark Ecdyo

Deep sea Sedge pupa: