Gangrene is the death of body tissue due to lack of blood flow and oxygen. There are several types of gangrene that can affect different areas of the body, including dry gangrene which affects extremities, wet gangrene which occurs with infection and swelling, and gas gangrene which is a serious bacterial infection. Symptoms vary depending on the type but may include pain, swelling, abnormal coloration and smell of affected areas. Treatment involves antibiotics, oxygen therapy, amputation or surgical removal of dead tissue in severe cases.