You create an alloy when you combine two or more elements where at least one has some sort of metallic property. Alloys can occur naturally, such as in gold, or they can be manufactured and used in modern technology.
Alloys are used in many aspects of everyday life. One example is steel, which is made up of the metal iron and carbon. Another example of an alloy is bronze, made by combining the metal copper with tin. Copper can also be blended with zinc to make the brass alloy.
The three main properties of metals are luster, malleability and conductivity. These properties are what makes metals so useful in creating alloys. Luster is the capacity of a metal to be shiny when cut (think of gold). Malleability means that you can take a metal, however strong, and bend it in a different shape, which is useful in the manufacturing of steel or bronze. Conductivity means the metal carries heat and electricity efficiently, a useful characteristic when manufacturing wire.