Copper alloys are metal alloys that have copper as their principal component. They have high resistance against corrosion. The best known traditional types are Bronze, where tin is a significant addition, and Brass, using zinc instead.

A brass is an alloy of copper with zinc. Brasses are usually yellow in colour. The zinc content can vary between few % to about 40%; as long as it is kept under 15%, it does not markedly decrease corrosion resistance of copper.

Bronze is a 80+% copper alloy and 90+% copper&tin alloy (commonly 12–12.5% tin) with often the addition of other metals, such as aluminium, manganese, nickel or zinc, and sometimes non-metals or metalloids such as arsenic, phosphorus or silicon.