Bone age is the degree of maturation of a child's bones. As a person grows from fetal life through childhood, puberty, and finishes growth as a young adult, the bones of the skeleton change in size and shape. These changes can be seen by x-ray techniques. The “bone age” of a child is the average age at which children reach various stages of bone maturation. A child's current height and bone age can be used to predict adult height. For most people, their bone age is the same as their biological age but for some individuals, their bone age is a couple of years older or younger. Those with advanced bone ages typically hit a growth spurt early on but stop growing sooner, while those with delayed bone ages hit their growth spurt later than normal. Children who are below average height do not necessarily have a delayed bone age; in fact their bone age could actually be advanced which if left untreated, will stunt their growth.