Nuzul Al-Quran - the Qur’an was revealed on this day, and this day commemorate this important occasion in Islam.
"In the month of Ramadhan the Al-Quran was revealed, a book of guidance for mankind with proofs of guidance distinguishing right from wrong..."
The day falls on the 17th day of Ramadan, (according to the Islamic calendar), and is a highlight of this holy month.