Casting is a manufacturing process in which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process. Casting materials are usually metals or various time-setting materials that cure after mixing two or more components together; examples are epoxy, concrete, plaster, and clay. Casting is most often used for making complex shapes that would be otherwise difficult or uneconomical to make by other methods. Heavy equipment like machine tool beds, ships' propellers, etc. can be cast easily in the required size, rather than fabricating by joining several small pieces.[1] Casting is a 7,000-year-old process. The oldest surviving casting is a copper frog from 3200 BC.

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Cast iron is a class of iron–carbon alloys with a carbon content of more than 2%.[1] Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its color when fractured; white cast iron has carbide impurities that allow cracks to pass straight through, grey cast iron has graphite flakes that deflect a passing crack and initiate countless new cracks as the material breaks and ductile cast iron has spherical graphite "nodules" which stop the crack from further progressing.

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Cast iron tends to be brittle, except for malleable cast irons. With its relatively low melting point, good fluidity, castability, excellent machinability, and resistance to deformation and wear resistance, cast irons have become an engineering material with a wide range of applications and are used in pipes, machines, and automotive industry parts, such as cylinder heads, cylinder blocks, and gearbox cases. It is resistant to damage by oxidation but is notoriously difficult to weld.

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The earliest cast-iron artifacts date to the 5th century BC, and were discovered by archaeologists in what is now Jiangsu, China. Cast iron was used in ancient China for warfare, agriculture, and architecture.[2] During the 15th century AD, cast iron became utilized for cannon in Burgundy, France, and in England during the Reformation. The amounts of cast iron used for cannons required large-scale production.[3] The first cast-iron bridge was built during the 1770s by Abraham Darby III and is known as the Iron Bridge in Shropshire, England. Cast iron was also used in the construction of buildings.