The birth anniversary of Prophet Spitaman Zarathushtra (Zoroaster), who founded Zoroastrianism, is celebrated as Khordad Sal. It falls sometime in August or September, on the sixth day of the Parsi month of Farvardin.

Similarly, the day of his birth is also not precisely known, and the fixing of Khordad Sal as his birthday is symbolical. The religious lore and texts of the Parsis mention the festival and its importance. In some old Parsi texts, this day is also spoken of as the Navroz-I-Khas, which means 'special new year's day', while the real New Year's day is referred to as Navroz-I-Am, meaning 'common new year's day'.

Clean, rangoli-strewn homes, children with vermilion spots on their foreheads, new clothes, fragrant flowers and delicious meals, all form part of the rituals. Jashan, or thanksgiving prayers, are offered to God in the agiaries. A grand feast is prepared to mark the occasion.