Moulding sand, also known as foundry sand, is a type of sand used to create moulds for metal casting. It is composed mainly of silica sand along with water and clay as binders. Moulding sand comes in different varieties depending on its composition and properties, including green sand, dry sand, loam sand, and others used for specific purposes like facing, backing, or creating cores. The key properties moulding sand requires are porosity to allow gas escape, adhesiveness, collapsibility after solidification, flowability to take the mould shape, sufficient refractoriness to withstand heat without melting, and cohesiveness for the sand particles to stick together.