Wolff's Law is a principle in orthopedics and bone biology that states bones adapt to the loads under which they are placed. This means that if a bone is subjected to increased stress or weight, it will remodel itself over time to become stronger and more resilient in response to that stress. Conversely, if a bone is not used or is under less stress, it may weaken and lose density. The law was named after the German surgeon Julius Wolff, who proposed this idea in the 19th century. It highlights the importance of physical activity and weight-bearing exercises in maintaining healthy bones, as regular stress can promote bone growth and strength.