Osteoporosis is a bone disease. It is characterized by a decreased bone mass and density, both of which make the bones fragile and increase the risk of fracture. Osteoporosis has no symptoms. It is a common condition that affects many people all over the world. There are usually no signs that one have developed osteoporosis and it often is being diagnosed after a bone fracture. Losing bone mass is a part of the normal ageing process. People start losing bone density after around 35 years of age. Women lose bone more rapidly during the first few years after the menopause.