Bread Crumbs are litterally
crumbs of
bread. They are used as an
ingredient in many different
recipes. They are made by allowing bread to
dry out, and then crumbling it up.
Often used in meat dishes to put a bread coating on the outside of the meat, like in chicken cutlets or fried chicken. In dishes made from ground beef, like meat balls or kabab kubideh, they help hold the form of the meat together while it cooks.
A tip from my old Italien Grandmother: wet the bread crumbs down with some water before making meat balls, it helps them come out nice and soft.