What's the difference between white meat and dark meat in poultry?

The main difference between white meat and dark meat in poultry is the amount of myoglobin, a protein that stores oxygen in muscles. White meat has less myoglobin and is found in muscles that are used for quick bursts of activity, like the breast. Dark meat has more myoglobin and is found in muscles that are used for sustained activity, like the legs and thighs. This difference in muscle usage affects the flavor, texture, and nutritional content of the meat.