An angel is a supernatural being in various Circum-Mediterranean religions. Abrahamic religions often depict them as benevolent celestial intermediaries between God (or Heaven) and humanity. Other roles include protectors and guides for humans, and servants of God. Abrahamic religions describe angelic hierarchies, which vary by sect and religion. Some angels have specific names (such as Gabriel or Michael) or titles (such as seraph or archangel). Humans have also used “angel” to describe various spirits and figures in other religious traditions. The theological study of angels is known as “angelology”. Those expelled from Heaven are called fallen angels, distinct from the heavenly host.