Zoroastrianism is an ancient Iranian religion founded by Zoroaster. It has around 2.6 million followers. Zoroastrians believe in one supreme god, Ahura Mazda, and that people should perform good deeds to achieve happiness. They use fire and water in important rituals, with fire representing spiritual insight and water representing wisdom. While there are some differences between Zoroastrianism and other major religions like Christianity and Judaism, they share many core beliefs around judgment after death, creation myths, and the roles of good and evil forces.