A hammer is a tool consisting of a weighted "head" attached to a long handle of an object. Hammers vary in shape, size and structure, depending on their use. Hammers used in many trades include heavy hammers and ball hammers. Hammers are used for general carpentry, framing, nailing, carpentry, furniture assembly, upholstery, finishing, riveting, bending or shaping metal, construction and drilling of wells in steel. The twisted shape also gives the hammer a nice forward spin.