An icon (from Greek
eikon, 'a picture') is a
tempera painting of a
saint, a
holy picture of the Eastern
Orthodox Church. Usually an icon is quite small (about 35 x 30cm) and painted on a thick
plank of wood. Icons are not framed, although sometimes they are covered by a sheet of some precious
metal (
riiza), leaving only the saint's hands and face visible.
The art of icon painting originates from the early Christian and Byzantine tradition. Even today, icons are still painted mainly on those areas where Byzantine influence has been strong during the Middle Ages. Thus, best icons are produced in Greece, Bulgaria, Russia, Romania and the Carelia region. Icon painting has flourished especially in Russia, where first icons were imported from Byzantium during the eleventh century AD. The greatest masters of Russian icon painting were Theofanes the Greek (Feofan Grek) and Andrei Rubljov, both of whom lived during the fourteenth century.
In an Orthodox church, icons are placed on a special wall (an iconostasis) and at home, they have a corner of their own. When a guest enters the house, he must cross himself and bow to the icons before even greeting his host, because an icon is more than just a religious picture. It is a symbol of the unity of all true believers and a reminder of the presence of God among them.
Since the purpose of the icons is to convey a religious message, only trained Orthodox painters are allowed to produce them. Strict rules govern every aspect of icon painting: the way colours are to be mixed (an icon artist must produce his own paints by mixing them with egg yolk), how the saints should be depicted, even the range of colours used.
There are various types of icons, categorized by their subject. Most popular ones portray the Christ, the Holy Trinity or the Virgin Mary. These categories are further divided by the state of the saint depicted. For example, Khristos Pantokrator is a king-like Jesus on his throne, and a Tender Virgin portrays Saint Mary pressing her cheek against the baby Christ.
OED & a few history of art lectures