A relief is a sculptured artwork where a modeled form projects out from a flat background.
Reliefs are a common type of artwork found throughout the world, particularly to decorate monumental buildings, such as temples. The frieze in the classical Corinthian order is often enriched with bas-relief (low relief). Alto-relievo (high-relief) may been seen in the pediments of classical temples, e.g. the Parthenon. Reliefs can be used for a single scene, or ordered into a narrative. They can be very detailed to the extent that even tensed musculature itself may be seen.
Several types of relief are commonly used and defined although in all cases the images must attach to the background.
Bas-relief (pronounced "bah"), or low relief, with the background compressed for depth; as seen for example in numismatics. Although unusual, Bas-relief may show faces and even bodies in natural relief.
Alto-relievo, of high relief, where the image is highly undercut and rendered almost in the round against its flat background. In alto-relief the figures are usually near natural depth and the background is more detailed and deeper.
Sunken-relief, also known as intaglio or hollow-relief, where the image is carved into the stone, creating in effect a negative, in contrast to other types of relief work where the surrounding stone is carved away to leave the image.