Aluminum foil is a thin, pliable metal leaf made of aluminum. It is the third most abundant element on earth and is extracted from bauxite, which is refined to make a pure aluminum oxide called alumina. The foil is 98.5% aluminum with the balance primarily from iron and silicon to give strength and puncture resistance.

Tin foil, which is a thin foil made of tin, was commercially available before its aluminum counterpart. However, it was superseded after World War II by cheaper and more durable aluminum foil, which is still referred to as "tin foil" in many regions. Tin foil is stiffer than aluminum foil and tends to give a slight tin taste to food wrapped in it, which is a major reason it has largely been replaced by aluminum and other materials for wrapping food.

Aluminum foil is used for a variety of purposes, including packaging of foods, cosmetics, and chemical products, as well as for industrial applications such as thermal insulation, electrical cables, and electronics. It is also a popular kitchen utility that is used worldwide for heating food in the oven or keeping food cold for many days. Aluminum foil is significantly cheaper to make than tin foil, which is another reason why it has become the preferred choice.