Mirza Husayn-Ali, who is known to the world by His title, Baha’u’llah, was born in Tehran, Iran on 12 November, 1817. Baha’u’llah means “Glory of God” in Arabic and He is the Prophet-Founder of the Baha’i Faith. The anniversary of the day He was born is celebrated alongside the Birth of the forerunner of His Revelation, the Bab. These Twin Holy Days are celebrated annually as one festival where the closely interwoven missions of these two Divine Luminaries are remembered together.
Sourced from https://www.bahaiblog.net/collection/calendar/the-birth-of-bahaullah