There are three main types of relief. The drawing of the distinction between high and low is often drawn differently, and in fact the two are very often combined in a single work - in particular most "high-reliefs" contain sections in "low-relief". Dashes may or may not be used in all these terms.
Bas-relief or low relief
A bas-relief ("low relief", French pronunciation: from the Italian basso rilievo) or low relief is the quality of a projecting image where the overall depth is shallow. The background is very compressed or completely flat, as on most coins, on which all images are in low-relief.
Lorenzo Ghiberti's gilded bronze "Doors of Paradise", Baptistery, Florence combine high relief main figures with backgrounds mostly in low relief.Bas-relief is very suitable for scenes with many figures and other elements such as a landscape or architectural background. A bas-relief may use any medium or technique of sculpture, but stone carving and metal casting are the traditional ones. If more than 50% of most rounded or cylindrical elements such as heads and legs project from the background, a sculpture is usually considered to be "alto rilievo" or "high relief", although the degree of relief within both types may vary across a composition, with prominent features such as faces in higher relief.
High relief
High relief (or alto relievo, from Italian) is where the most prominent elements of the composition are undercut and rendered at more than 50% in the round against the background.
All cultures and periods where large sculptures were created used this technique as one of their sculptural options. Seen in "monumental sculpture" and architecture from ancient times to present.
Sunken relief
Sunken-relief depiction of Pharaoh Akhenaten with his wife Nefertiti and daughters. Note how strong shadows are needed to define the image.Sunken-relief, also known as intaglio or hollow-relief, is where the image is made by carving into a flat surface - usually the images are mostly linear in nature. It is most notably associated with the Art of Ancient Egypt, where the strong sunlight usually needed to make the technique successful for images is present most of the time. In the sculpture of many cultures, including Europe, it is mostly used for inscriptions and engraved gems - the most likely meaning for "an intaglio
