Aluminum is commonly used in aircraft bodies because it is lightweight and corrosion-resistant. It is element 13 and is called aluminium in British English and aluminum in American English.
Aluminum has a low density compared with iron and many other structural metals. Its surface quickly forms a thin oxide layer when exposed to air, helping protect the underlying metal from further corrosion. These properties made aluminum especially valuable as aviation developed during the twentieth century.
Aircraft are generally made from aluminum alloys rather than pure aluminum. Elements such as copper, magnesium, silicon, and zinc can increase strength while preserving relatively low weight. Modern aircraft also use composites and titanium in selected areas, but aluminum remains historically and industrially important.
Aluminum is not naturally found as free metal in ordinary rocks because it reacts readily with oxygen. Industrial production commonly begins with bauxite ore, which is refined into alumina and then processed by electrolysis. Recycling aluminum requires far less energy than producing it from ore.