A comet is a small celestial body that orbits the Sun, composed mainly of ice, dust, and rocky material. When a comet approaches the Sun, it heats up and releases gases, forming a glowing coma and often a tail that points away from the Sun due to solar wind. Famous comets include Halley's Comet, which is visible from Earth approximately every 76 years. Comets are believed to originate from two main regions in the solar system: the Kuiper Belt and the Oort Cloud. They provide valuable insights into the early solar system and the formation of planets, making them important subjects of study in astronomy.