What do you call the thing you put your sleeping bag in?

My troop always just calls them a stuff sack or a sleeping bag bag. I'm not sure if there is a better name. There are ones called compression sacks that makes it smaller, maybe that's it?

when i was a kid and we would go camping we always rolled our sleeping bags. When i started looking at bags for backpacking I learned that the bag will actually "stuff" smaller if you just stuff it into the stuff sack instead of trying to roll it up first. it won't harm the bag although if it is a down bag once you are finished with your trip you should not store it in the stuff sack it can crush the loft of the down and make it not perform as well at the lower range of the rating.

Tarp with compression straps. It makes big bags compact (smaller) and protects it from stain, tear or wet. It can be rigged over small tent as rain fly, something to hoist food stores out of wildlife reach, or ground cover if soil is damp.