Gangrene is the death of body tissue due to reduced blood flow and loss of oxygen. It can be caused by infection, injury, or conditions that damage blood vessels like diabetes. There are three main types of gangrene: dry gangrene affects areas with no moisture and tissues become shriveled and black; wet gangrene occurs in moist tissues and causes swelling and foul odors; gas gangrene is a deadly infection that produces gas in tissues and can spread rapidly. Treatment depends on the type and severity but may include antibiotics, restoring blood flow surgically, or amputating dead tissue.