Bronze is an alloy consisting primarily of copper and other metals. The addition of other metals (usually tin, sometimes arsenic or lead), produces an alloy much harder than plain copper. The Terran historical period where the archaeological record contains many bronze artifacts is known as the Bronze Age.
Because historical pieces were often made of brasses (copper and zinc) and bronzes with different compositions, modern museum and scholarly descriptions of older objects increasingly use the more inclusive term "copper alloy" instead
In the Bronze Age, two forms of bronze were commonly used: "classic bronze", about 10% tin, was used in casting; and "mild bronze", about 6% tin, was hammered from ingots to make sheets. Bladed weapons were mostly cast from classic bronze, while helmets and armor were hammered from mild bronze.
Typically modern bronze is 88% copper and 12% tin.