Bronze is one of the earliest metals known to man. It is defined as an alloy made of copper and another metal, usually tin. Compositions vary, but most modern bronze is 88% copper and 12% tin. Bronze may also contain manganese, aluminum, nickel, phosphorus, silicon, arsenic, or zinc. Although, at one time, bronze was an alloy consisting of copper with tin and brass was an alloy of copper with zinc, modern usage has blurred the lines between brass and bronze. Now, copper alloys generally are called brass, with bronze sometimes considered a type of brass.

Source: Thought.Co