Osteoporosis is a progressive bone disease characterized by low bone mass and deterioration of bone tissue, leading to fragile bones that are prone to fracture. It is defined as a bone density 2.5 standard deviations below peak bone mass. Osteoporosis commonly affects older individuals, especially postmenopausal women. Risk factors include age, sex, family history, hormone changes, poor diet, medications, and medical conditions. Diagnosis involves tests like DEXA scans and quantitative CT scans. Treatment includes lifestyle changes, calcium and vitamin D supplementation, bisphosphonates, and other drugs that reduce bone resorption or increase bone formation to manage the disease and prevent fractures.