Au is the chemical symbol for gold.
The symbol comes from the Latin word aurum, meaning gold or shining dawn, rather than from the English name. Gold has atomic number 79 and is a dense, highly malleable metal prized for its resistance to corrosion. Its symbol uses a capital A followed by a lowercase u, as required by the conventions of chemical notation.
Gold has been known and worked by humans since prehistoric times. Ancient Egyptian, Mesopotamian, and South American societies used it for ornaments, ritual objects, and currency. The element’s distinctive yellow colour and chemical stability helped make it a monetary standard in many historical economies. Silver is Ag, from argentum, while iron is Fe, from ferrum; these Latin-derived symbols are common sources of confusion. Gd represents gadolinium, a different element with atomic number 64.