CDC question

I am thinking of tying my first dry flies and considering using cdc. What is cdc and why use it? Also, can if be found at hobby stores or is it a fly tyining material exclusively?

Thanks for the help.

It's an abbreviation for cul de(du?) canard, which is basically the feathers from around a duck's butt-area. They are good because they float well. Some people think they float well because of the oil from the gland, but that stuff basically all gets washed away during the commercial preparation and they still float just as well. I've never seen them in craft stores, but they are fairly inexpensive from the various tying sites and shops.

reads this

http://www.flyfisherman.com/content/simplifying-cdc