Osteoporosis is a disease where bones become fragile and more likely to break, affecting over 28 million Americans, mostly women. It is caused by bone loss increasing faster than bone formation as people age. Risk factors include family history, small frame, smoking, excessive alcohol, lack of exercise, and low calcium/vitamin D intake. While there is no cure, lifestyle changes like weight-bearing exercise, adequate calcium and vitamin D, not smoking, and medications can help prevent osteoporosis and fractures.