A distinction exists between sculpture "in the round", free-standing sculpture such as statues, not attached except possibly at the base to any other surface, and the various types of relief, which are at least partly attached to a background surface. Relief is often classified by the degree of projection from the wall into low or bas-relief, high relief, and sometimes an intermediate mid-relief. Sunk-relief is a technique restricted to ancient Egypt. Relief is the usual sculptural medium for large figure groups and narrative subjects, which are difficult to accomplish in the round, and is the typical technique used both for architectural sculpture, which is attached to buildings, and for small-scale sculpture decorating other objects, as in much pottery, metalwork and jewellery. Relief sculpture may also decorate steles, upright slabs, usually of stone, often also containing inscriptions.

Another basic distinction is between subtractive carving techniques, which remove material from an existing block or lump, for example of stone or wood, and modelling techniques which shape or build up the work from the material. Techniques such as casting, stamping and moulding use an intermediate matrix containing the design to produce the work; many of these allow the production of several copies.

The term "sculpture" is often used mainly to describe large works, which are sometimes called monumental sculpture, meaning either or both of sculpture that is large, or that is attached to a building. But the term properly covers many types of small works in three dimensions using the same techniques, including coins and medals, hardstone carvings, a term for small carvings in stone that can take detailed work.

The very large or "colossal" statue has had an enduring appeal since antiquity; the largest on record at 182 m (597 ft) is the 2018 Indian Statue of Unity. Another grand form of portrait sculpture is the equestrian statue of a rider on horse, which has become rare in recent decades. The smallest forms of life-size portrait sculpture are the "head", showing just that, or the bust, a representation of a person from the chest up. Small forms of sculpture include the figurine, normally a statue that is no more than 18 inches (46 cm) tall, and for reliefs the plaquette, medal or coin.

Modern and contemporary art have added a number of non-traditional forms of sculpture, including sound sculpture, light sculpture, environmental art, environmental sculpture, street art sculpture, kinetic sculpture (involving aspects of physical motion), land art, and site-specific art. Sculpture is an important form of public art. A collection of sculpture in a garden setting can be called a sculpture garden. There is also a view that buildings …

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One of the most common purposes of sculpture is in some form of association with religion. Cult images are common in many cultures, though they are often not the colossal statues of deities which characterized ancient Greek art, like the Statue of Zeus at Olympia. The actual cult images in the innermost sanctuaries of Egyptian temples, of which none have survived, were evidently rather small, even in the largest temples. The same is often true in Hinduism, where the very simple and ancient form of the lingam is the most common. Buddhism brought the sculpture of religious figures to East Asia, where there seems to have been no earlier equivalent tradition, though again simple shapes like the bi and cong probably had religious significance.

Small sculptures as personal possessions go back to the earliest prehistoric art, and the use of very large sculpture as public art, especially to impress the viewer with the power of a ruler, goes back at least to the Great Sphinx of some 4,500 years ago. In archaeology and art history the appearance, and sometimes disappearance, of large or monumental sculpture in a culture is regarded as of great significance, though tracing the emergence is often complicated by the presumed existence of sculpture in wood and other perishable materials of which no record remains;

The totem pole is an example of a tradition of monumental sculpture in wood that would leave no traces for archaeology. The ability to summon the resources to create monumental sculpture, by transporting usually very heavy materials and arranging for the payment of what are usually regarded as full-time sculptors, is considered a mark of a relatively advanced culture in terms of social organization. Recent unexpected discoveries of ancient Chinese Bronze Age figures at Sanxingdui, some more than twice human size, have disturbed many ideas held about early Chinese civilization, since only much smaller bronzes were previously known.

Some undoubtedly advanced cultures, such as the Indus Valley civilization, appear to have had no monumental sculpture at all, though producing very sophisticated figurines and seals. The Mississippian culture seems to have been progressing towards its use, with small stone figures, when it collapsed. Other cultures, such as ancient Egypt and the Easter Island culture, seem to have devoted enormous resources to very large-scale monumental sculpture from a very early stage.

The collecting of sculpture, including that of earlier periods, goes back some 2,000 years in Greece, China and Mesoamerica, and many collections were available on semi-public display long before the modern museum was invented. …

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The materials used in sculpture are diverse, changing throughout history. The classic materials, with outstanding durability, are metal, especially bronze, stone and pottery, with wood, bone and antler less durable but cheaper options. Precious materials such as gold, silver, jade, and ivory are often used for small luxury works, and sometimes in larger ones, as in chryselephantine statues. More common and less expensive materials were used for sculpture for wider consumption, including hardwoods (such as oak, box/boxwood, and lime/linden); terracotta and other ceramics, wax (a very common material for models for casting, and receiving the impressions of cylinder seals and engraved gems), and cast metals such as pewter and zinc (spelter). But a vast number of other materials have been used as part of sculptures, in ethnographic and ancient works as much as modern ones.

Sculptures are often painted, but commonly lose their paint to time, or restorers. Many different painting techniques have been used in making sculpture, including tempera, oil painting, gilding, house paint, aerosol, enamel and sandblasting.

Many sculptors seek new ways and materials to make art. One of Pablo Picasso's most famous sculptures included bicycle parts. Alexander Calder and other modernists made spectacular use of painted steel. Since the 1960s, acrylics and other plastics have been used as well. Andy Goldsworthy makes his unusually ephemeral sculptures from almost entirely natural materials in natural settings. Some sculpture, such as ice sculpture, sand sculpture, and gas sculpture, is deliberately short-lived. Recent sculptors have used stained glass, tools, machine parts, hardware and consumer packaging to fashion their works. Sculptors sometimes use found objects, and Chinese scholar's rocks have been appreciated for many centuries.
Stone sculpture is an ancient activity where pieces of rough natural stone are shaped by the controlled removal of stone. Owing to the permanence of the material, evidence can be found that even the earliest societies indulged in some form of stone work, though not all areas of the world have such abundance of good stone for carving as Egypt, Greece, India and most of Europe. Petroglyphs (also called rock engravings) are perhaps the earliest form: images created by removing part of a rock surface which remains in situ, by incising, pecking, carving, and abrading. Monumental sculpture covers large works, and architectural sculpture, which is attached to buildings. Hardstone carving is the carving for artistic purposes of semi-precious stones such as jade, agate, onyx, rock crystal, sard or carnelian, and a general term for an object made in this way. Alabaster or mineral gypsum is a soft mineral that is easy to carve for smaller works and still relatively durable. Engraved gems are small carved gems, including cameos, originally use…

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