Sculpture is a three-dimensional art form created by shaping hard materials like stone, metal, glass, or wood. There are three main types of sculpture: subtractive, which involves removing material like in carving; additive, which is most common today and involves adding material; and kinetic, containing moving parts. Sculpture is created through four basic processes - carving, modeling, casting, and construction - and can also involve assemblage, relief, or kinetic elements.