Metallurgy is also known as metal technology, which is the application of science to the manufacturing of metals and the engineering of metal components for use in goods for manufacturers and customers. Essentially, it is the study of minerals and their transformation into products that have utility for humans. Metallurgy includes mining for minerals, milling to remove impurities, refining to remove unwanted substances such as oxygen and carbon, and casting or forming processes for shaping metals at room temperature or under pressure. The end products are often tools, containers, or electronic components. Alloys: mixtures of two or more materials that have a single unified element in common. Alloys can be divided up into three main categories: ferrous (containing iron), nonferrous (not containing iron), and mixed (containing elements from both groups). Iron is the most abundant metal on earth. Other common metals used in alloys include cobalt, copper, nickel, phosphorus, silver, zinc. Alloys are used in many everyday products, including cutlery, HVAC systems, and vehicles. They are also used extensively in industry because they provide advantages unique to each composition. For example, steel is used because it's strong and can be formed into desired shapes. Aluminum is used because it's lightweight and does not oxidize.