What is relief?
There are different degrees of relief depending on the degree of projection of the sculpted form from the field, for which the Italian appellations are still sometimes used. The full range includes high relief (alto-rilievo), where more than 50% of the depth is shown and there may be undercut areas, mid-relief (mezzo-rilievo), low-relief (basso-rilievo, or French:bas-relief), and shallow-relief or rilievo schiacciato, where the plane is scarcely more than scratched in order to remove background material. There is also sunk relief, which was mainly restricted to Ancient Egypt. However the distinction between high relief and low relief is the clearest and most important, and these two are generally the only terms used to discuss most work. The definition of these terms is somewhat variable, and many works combine areas in more than one of them, sometimes sliding between them in a single figure; accordingly some writers prefer to avoid all distinctions.The opposite of relief sculpture is counter-relief, intaglio, or cavo-rilievo, where the form is cut into the field or background rather than rising from it; this is very rare in monumental sculpture.
Reliefs are common throughout the world on the walls of buildings and a variety of smaller settings, and a sequence of several panels or sections of relief may represent an extended narrative. Relief is more suitable for depicting complicated subjects with many figures and very active poses, such as battles, than free-standing "sculpture in the round". Most ancient architectural reliefs were originally painted, which helped to define forms in low relief. The subject of reliefs is for convenient reference assumed in this article to be usually figures, but sculpture in relief often depicts decorative geometrical or foliage patterns, as in the arabesques of Islamic art, and may be of any subject.