The art of making images by arranging small colored pieces of glass or stone is called mosaic. The individual pieces are known as tesserae, and they are usually fixed to a surface with mortar, plaster, or adhesive to create a unified pattern or picture.
Mosaic has an exceptionally long history. Some of the earliest known examples come from Mesopotamia in the 3rd millennium BCE, while pebble mosaics later flourished in ancient Greece and Rome. Roman artists used mosaics for floors, walls, and decorative scenes; Byzantine artists developed especially luminous wall and ceiling mosaics using colored glass, gold leaf, and symbolic religious imagery.
Mosaics are distinguished from related arts by their assembled pieces. A tapestry is woven, a fresco is painted into wet plaster, and a collage normally combines attached materials such as paper or fabric. Mosaic pieces can be regular or irregular and may be made from marble, ceramic, shells, mirror, or modern found objects. The word “tessera” comes from a term meaning a small four-sided piece, though mosaic pieces are not always square.