Ductility is a solid material’s ability to deform under tensile stress; this is often characterized by the material’s ability to be stretched into a wire.
Malleability, a similar property, is a material’s ability to deform under compressive stress; this is often characterized by the material’s ability to form a thin sheet by hammering or rolling. Both of these mechanical properties are aspects of plasticity, the extent to which a solid material can be plastically deformed without fracture.