Malleability is a mechanical property of matter, but is most commonly use in reference to metals and metalloids. A malleable metal is capable of being flattened into thin sheets without cracking by the processes of hammering or rolling. This property is important in metalworking, as materials that crack or break under pressure cannot be hammered or rolled. Malleable materials can be formed using stamping or pressing, whereas brittle metals and plastics must be molded.