A "halo" is a circular band of light that appears to surround the sun or moon, often seen in the sky. This optical phenomenon occurs when sunlight or moonlight interacts with ice crystals in the atmosphere, typically found in cirrus clouds. The halo can appear as a bright white circle or may display colors, resembling a rainbow. In addition to its natural occurrence, the term "halo" is also used in various cultural and religious contexts. For example, in art, a halo often represents holiness and is depicted as a glowing circle around the heads of angels or saints.