http://www.practicallyedible.com/edible.nsf/pages/stewingbeef said:
Stewing Beef is bite-sized boneless pieces of tough beef used for stews and similar dishes. Excess fat and any gristle are usually trimmed away for you.
The beef selected is meat which would require long, slow cooking anyway to make it tender. It is usually cut from the Chuck or Round; it can also come from the Shank, Neck, Clod or Plate sections.
Stewing Beef is fine from anywhere in the cow, but if you have any choice and if price makes no difference, consider meat from the Chuck, at the front part of the cow. The front part of the cow does more work, as it basically pulls the cow and the hind bit follows, so there are more ligaments and muscle tissue in the front. This is bad news for a barbeque, but good news for a stew, as long, slow heat gelatinizes collagen in this tissue, which is nice in a stew. As an added bonus, there's more fat at the front than at the relatively lean back end, fat that bastes the meat during this long cooking to keep it juicy.