Chuck, rib, round and loin are four basic cuts of beef. Each cut comes from a specific part of a cow. The name of the cut typically refers to the body part it is extracted from.
Chuck comes from the shoulder and neck region. Chuck products include ground chuck, steak and roast. Chuck steak, occasionally sold as blade chuck, is typically 1-inch thick and rectangular in shape. Rib refers to any cut of meat from the rib section of a cow, including the back ribs, ribeye steak and ribeye roast..
Beef round cuts come from the rear of a cow's leg, specifically the meat of the upper leg. Round includes the sub-categories eye of round, bottom round and top round. Round cuts are low in fat, and they are best for stews or cooking methods involving liquid, such as braising. Eye of round tends to be the lowest in fat and the driest, whereas bottom and top round have slightly more marbling or fat.
Loin, short loin, sirloin, top sirloin and tenderloin are cuts from the same overall region of a cow. Beef loin encompasses most of the meat below the rib cage and in front of the hind legs. The tenderloin, or backstrap, are twin tear-shaped muscles running parallel to the backbone of a cow.
Sirloin is closest to the back of the cow. It is the source of T-bone and porterhouse steaks. Top and bottom sirloin merely indicate degrees of tenderness, with top being more tender than bottom.