Gangrene is a serious and potentially life-threatening condition that arises when a considerable mass of body tissue dies (necrosis). This may occur after an injury or infection, or in people suffering from any chronic health problem affecting blood circulation. The primary cause of gangrene is reduced blood supply to the affected tissues, which results in cell death.Diabetes and long-term smoking increase the risk of suffering from gangrene.

There are different types of gangrene with different symptoms, such as dry gangrene, wet gangrene, gas gangrene, internal gangrene and necrotising fasciitis. Treatment options include debridement (or, in severe cases, amputation) of the affected body parts, antibiotics, vascular surgery, maggot therapy or hyperbaric oxygen therapy.

Gangrene is caused by infection or ischemia, such as by the bacteria Clostridium perfringens or by thrombosis (a blocked blood vessel). It is usually the result of critically insufficient blood supply (e.g., peripheral vascular disease) and is often associated with diabetes and long-term smoking. This condition is most common in the lower extremities. The best treatment for gangrene is revascularization (i.e., restoration of blood flow) of the affected organ, which can reverse some of the effects of necrosis and allow healing. Other treatments include debridement and surgical amputation. The method of treatment is, in general, determined depending on location of affected tissue and extent of tissue loss. Gangrene may appear as one effect of foot binding.

Marco Polo (ⁱ/ˈmɑrkoʊ ˈpoʊloʊ/; Italian pronunciation: [ˈmarko ˈpɔːlo]; c. 1254 – January 9, 1324) was a Venetian merchant traveler from the Venetian Republic whose travels are recorded in Il Milione, a book which did much to introduce Europeans to Central Asia and China. He learned about trading whilst his father and uncle, Niccolò and Maffeo, travelled through Asia and apparently met Kublai Khan. In 1269, they returned to Venice to meet Marco for the first time. The three of them embarked on an epic journey to Asia, returning after 24 years to find Venice at war with Genoa; Marco was imprisoned, and dictated his stories to a cellmate. He was released in 1299, became a wealthy merchant, married and had three children. He died in 1324, and was buried in San Lorenzo.

Their pioneering journey inspired Christopher Columbus and others. Marco Polo's other legacies include Venice Marco Polo Airport, the Marco Polo sheep, and several books and films. He also had an influence on European cartography, leading to the introduction of the Fra Mauro map.