The Halo became a standard feature in sacred art of the angel and of all heavenly beings by the 4th century C.E. The halo signifies divine radiance, and marks membership in the Kingdom of Light -- representing nearness to God.
The ancient Egyptians, Greeks, Indians and Romans used halos to depict supernatural force, mystical states and superior intellect. In Egypt and Greece the halo was associated with the sun and with resurrection. In the Eleusinian mysteries the sacrificed and reborn god, usually Dionysus, was portrayed with a halo.
In Christian art the saints, Jesus and the Virgin Mary wear halos, as do the angels.
In the East, crowns and headdresses substitute for halos, but bear the same significance. A halo or crown also can be seen as the radiance of the crown chakra, which is prominent in persons of advanced spiritual development.