Osteoporosis is a medical condition characterized by weakened bones that become fragile and more susceptible to fractures. It occurs when the body loses too much bone mass, makes too little bone, or both, often due to hormonal changes, nutritional deficiencies, or aging. Common risk factors include being postmenopausal, having a family history of the disease, and lack of physical activity. Preventative measures include a balanced diet rich in calcium and vitamin D, regular weight-bearing exercises, and avoiding smoking and excessive alcohol consumption.