An angel is a supernatural spiritual being who, according to various religions, is God's servant. Abrahamic religions often depict angels as benevolent celestial intermediaries between God and humanity. Other roles include protectors and guides for humans, and servants of God. Abrahamic religions describe angelic hierarchies, which vary by religion and sect. Some angels have specific names or titles. Those expelled from Heaven are called fallen angels, distinct from the heavenly host. Angels in art are usually shaped like humans of extraordinary beauty. They are often identified in Christian artwork with bird wings, halos, and divine light.