Alloys are homogeneous mixtures of two or more metals or a metal and a non-metal. Alloys can not be separated into their components by physical methods. But still, an alloy is considered as a mixture because it shows the properties of its constituents as well as some improved properties and they can have variable composition. Brass is a mixture of approximately 30% zinc and 70% copper. Steel is an alloy of 95 to 99 % Fe and 1 to 5 % carbon. Bronze is an alloy of copper and tin. Twenty two carat gold is an alloy of gold and copper.

Alloys of aluminium are used in aeroplanes. Alloys of magnesium are used in making domestic utensils. Gun metal, german silver, stainless steel, fuse wire are some more examples of alloys.