. Nasty. It's moist, smelly, a lot of work to clean out, attracts flies, and a great environment for red mites, ticks, fleas and parasites. If you want a minimal labor bedding, clean, dry, healthy, cheap and virtually NO ODOR, then sand is the way to go!! Go Here to see my blog post on coop management with sand. It is HEAVENLY!!!!
As long as you keep the area dry. Deep litter shouldn't smell or attract flies.
So back to your question. Deep litter is the process of dry composting in the run or house. People do this many different ways. What works for me starts with fresh pine shavings. My shavings start in the house where I keep adding and they keep breaking them down until it's full and I rake them out into the covered run where they break them down further by scratching and doing various chicken things. When the run is full I wheel barrow it out to the compost pile where other things get added and the chickens continue scratching and breaking things down. This happens about twice a year. Spring and Fall. I add the compost from the pile to the garden in early spring before adding the spring clean out to the pile. I also add a layer of DE to the run and house when I do a clean out. The girls mix it in.
Sometimes things can get damp in the run. I then just add some from the house.
Kanna explained it well. The idea is, instead of cleaning out the coop all the time, you layer bedding in a way that allows it to compost. You need to start with a thick layer. The poop will mix in and the chickens will turn it all as they move around. You need to keep layering new bedding in. If you keep the bedding and poop balanced it will not smell or be gross. If it starts to smell your balance is off. It should never be moist. If it is moist you need to clean out and start over.