Twisted Leaders

I was searching the web tonight, mainly resting due to not feeling so well, I came across this How to make twised leaders. Can someone fill me in as to How and Why they are used. It seems to me as if they would get all tangled up when casting. Can they be used for surf fishing or are they just for deep sea?

http://castflys.net/Documents/Twisted.pdf

These are used for fly casting. With this size I would have to assume its for big game fishing. A tapered leader is for ease of casting and the tippet is for tying the fly to in order to not having to cut away from the tapered leaders.

Dang. I saw the name of this thread and thought they had some dirt on Frankie :naughty: