Brisket is cut from the underside of the cow near the chest area. This part of the cow is tough because of the high collagen and fat content.
Brisket comes in two cuts: the flat and the point. These can be purchased undivided or separate. It also comes in trimmed or untrimmed. Untrimmed has a layer of fat on top and a strip of fat running through the middle. Untrimmed, undivided brisket is referred to as a "packer's cut."
Despite coming from one of the toughest parts of the cow, it is the collagen content that gives smoked brisket its flavor. Collagen cooks down into gelatin slowly at low temperatures. To keep the brisket moist during cooking, choose a piece with good marbling.