An alloy is a mixture of two separate types of metal, to create a stronger, more usable result.
For example, bronze is the alloy of copper and tin. Alloy creation played an important role in early human history: the discovery of the value of bronze, for example, spurred an increase in human tool development and metallurgy, spurring cultural, scientific, and technological advances. This period of history, known as the Bronze Age, occurred very early in the history of the world. Another important alloy, steel, has defined the modern industrial era.