Ashura is a significant day in Islam, particularly for Shia Muslims, marking the martyrdom of Hussein, the Prophet Muhammad's grandson, at the Battle of Karbala. It also commemorates the day Noah left the Ark and when Moses was saved from the Egyptians. While both Sunni and Shia Muslims acknowledge Ashura, its observance differs, with Shia Muslims engaging in mourning rituals and passionate re-enactments of the events of Karbala.