There probably is not much that can be said about the Wooly Bugger that havn't been said before. Love it or hate it, it should be in everyone's fly box as it is a proven fish catcher from Trout, Bass, Bluegills, Carp, etc.
From What I can gather a Pennsylvania fly tier, Russell Blessing tied the first "Buggers". He added a marabou tail to a woolly worm fly, to help suggest a swimming movement as the fly was retrieved in the water.The Wooly worm is very old and was already mentioned in Izaak Walton 1653 book "The Compleat Angler". The original Woolly Bugger was tied to imitate the Dobsonfly Lava.
Woolly Buggers suggest lots of different trout food: Dragonfly nymphs, damselfly nymphs, leeches, baitfish, or just something that might be alive and edible.
To fish the Whoolly Bugger you can use a countdown and retrieve or slow retrieve. Vary the retrieve until you find what works best at the moment, slow and steady, fast, strip and pause, or what ever works for the fish on the day.
Below is my favorite variation.
TAIL: Olive Marabou
FLASH: Crystal flash
BODY: Seals fur dubbing