Icon [Gr. eikon=image], single image created as a focal point of religious veneration, especially a painted or carved portable object of the Orthodox Eastern faith. Icons commonly represent Christ Pantocrator, the Virgin as Queen of the Heavens, or, less frequently, the saints; since the 6th cent. they have been considered an aid to the devotee in making his prayers heard by the holy figure represented in the icon. The icon grew out of the mosaic and fresco tradition of early Byzantine art. It was used to decorate the wall and floor surfaces of churches, baptisteries, and sepulchers, and later was carried on standards in time of war and in religious processions. Although the art form was in common use by the end of the 5th cent., early monuments have been lost, largely because of their destruction during the iconoclastic controversy (726–843; see iconoclasm). Little has survived that was created before the 10th cent. Byzantine icons were produced in great numbers until 1453, when Constantinople fell to the Ottoman Empire. The practice was transplanted to Russia, where icons were made until the Revolution. The anonymous artists of the Orthodox Eastern faith were concerned not with the conquest of space and movement as seen in the development of Western painting but instead with the portrayal of the symbolic or mystical aspects of the divine being. The stiff and conventionalized appearance of icons may bear some relationship to the two-dimensional, ornamental quality of the Eastern tradition. It is this effect more than any other that causes the icons in Byzantine and later in Russian,  Greek and Serbian Orthodox art to appear unchanging through the centuries; there is, however, a stylistic evolution in Byzanto-Russian art that can be seen through variations of a standard theme by local schools rather than through the development of an art style by periods. The term icon came to mean “subject matter” in the 19th-century German school of art historical study, and from this meaning were derived the terms iconography and iconology.