A foil is a very thin sheet of metal, typically made by hammering or rolling.
[1][2] Foils are most easily made with malleable metal, such as aluminium, copper,[3] tin, and gold.
[2] For example, aluminium foil is usually about 1⁄1000 inch (0.025 mm), whereas gold (more malleable than aluminium) can be made into foil only a few atoms thick, called gold leaf.
Extremely thin foil is called metal leaf.
Leaf tears very easily and must be picked up with special brushes.