Aluminium foil acts as a total barrier to light and oxygen (which cause fats to oxidise or become rancid), odours and flavours, moistness, and germs, and so it is used broadly in food and pharmaceutical packaging, including long-life packs for drinks and dairy goods, which allows storing without refrigeration.
Aluminium foil is aluminium prepared in thin metal leaves. The foil is pliable and can be readily bent or wrapped around objects. Thin foils are fragile and are sometimes laminated with other materials such as plastics or paper to make them stronger and more useful.