Marbling refers to the white streaks of fat that run through beef, similar to veins of color running through a piece of marble. This fat melts during cooking, providing extra flavor and keeping the meat moist. Meat with a higher amount of marbling is generally juicier and can be cooked quickly without a loss of flavor or texture. Lean cuts of beef have little marbling and are best cooked slowly. Most ribeye roasts are well-marbled and juicy.