The first basic classification of sculpture is based on its appearance, which is sculpture in the round or relief, and the other distinction classifies it based on its method of creation, which is additive or subtractive. Sculpture in the round is a free standing sculpture, which is not attached to any background. An example of a sculpture in the round is Michelangelo's David.
A relief sculpture is attached to a background, such as a wall. An example of a relief sculpture is the Parthenon Marbles. A sculpture is known as subtractive when material is removed to create the sculpture, such as stone sculptures or wood carving. Additive sculptures are formed by adding materials, such as clay to produce various forms. Modeling is a form of additive sculpture where a soft material, such as wax or clay is added to mold a shape.