An aluminum alloy is a composition consisting mainly of aluminum to which other elements have been added. The alloy is made by mixing together the elements when aluminum is molten (liquid), which cools to form a homogeneous solid solution. The other elements may make up as much as 15 percent of the alloy by mass. Added elements include iron, copper, magnesium, silicon, and zinc. The addition of elements to the aluminum gives the alloy improved strength, workability, corrosion resistance, electrical conductivity, and/or density, compared with the pure metallic element. Aluminum alloys tend to be lightweight and corrosion resistant. Aluminum alloys are incredibly versatile, sturdy, and reliable. For this reason, they are very sought-after in engineering, construction, and automotive applications, making for one of the most widespread metal materials, alongside steel.