An alloy is a mixture of two elements, one of which is a metal.
Alloys often have properties that are different from the metal they contain example strength, hardness, durability, ductility, tensile strength and toughness.
This makes them more useful than pure metalsalone.
Eg: Bronze (copper and tin), is used to make bells, hammers etc
Steels from iron alloys are used to make car bodies and railway lines.