Aluminium is a lightweight metal (its mass is only a third that of steel or iron). Nevertheless, it is both durable and corrosion-resistant. In addition, aluminium is relatively easy to process and form, making it an excellent building material. In contrast with all other metals, aluminium is used in a very wide range of applications. The aluminium that is collected for recycling is usually re-smelted into ingots. There are different categories of aluminium, namely used, cast and profile, which are used as the basis for pricing.