An angel is a supernatural being or spirit found in various religions and mythologies. In Zoroastrianism and Abrahamic religions they are often depicted as benevolent celestial beings who act as intermediaries between Heaven and Earth, or as guardian spirits or a guiding influence. Other roles of angels include protecting and guiding human beings, and carrying out God’s tasks. The term “angel” has also been expanded to various notions of spirits found in many other religious traditions. The theological study of angels is known as “angelology”. In art, angels are often depicted with bird-like wings on their back, a halo, robes and various forms of glowing light.