What cut of beef does corned beef come from?
Beef brisket is the cut used to make corned beef. A primal cut, it's a large piece from the breast or lower chest of beef cattle. Brisket is a tough cut with connective tissue throughout, and a whole brisket typically weighs 10 pounds or more. When it's cooked whole, it's usually served as a roast or barbecued brisket. Otherwise, it's cut into flat and point cuts. Many cooks are confused about which of these to buy, though they're actually quite similar.
Why is it called corned beef?
First off, it has nothing to do with corn. The term "corned" comes from the English and it refers to small particles. "Corn" refers to the larger-grained rock salt, which is used to cure the beef.