Casting is the process in which metal is heated to make it molten and then poured into a mould. Most metallic materials pass through a molten state at some stage during the shaping process. Generally, molten metal is cast into ingot form prior to being shaped by some mechanical working process. However, some metals and alloys – and a number of non-metallic products such as concrete – can be shaped only by casting since they lack the necessary properties of either malleability or ductility which make them amenable to working processes. This chapter is about the casting processes used with metals.