The Twin Holy Days, namely the anniversaries of the birthdays of the Báb and Bahá’u’lláh, are celebrated on two consecutive days in October / November (ʻIlm / Qudrat).
The Báb was a messenger of God (a divine educator) and the predecessor of Bahá’u’lláh. He prepared the people for Bahá’u’llah’s coming, announcing that Bahá’u’lláh would possess the keys to the unification of the entire human race. The Báb’s given name was Siyyid ‘Alí Muḥammad; He was born in the city of Shiraz in Persia (modern-day Iran) in 1819.