One of the primacy of Ramadan is the month in which the Qur'an is revealed. This came to be known as 'Nuzulul Quran'. This is supported by QS. Albaqarah 185.
شهر رمضان الذى انزل فيه القرأن هدى للناس وبينت من الهدى والفرقان
Meaning: The few prescribed days are: The Ramadan, the month in which the Qur'an begins to guide the human and explanations of the clues and the distinctions (between haq and the bathil).
Nuzulul Qur’an is the night of lowered revelation for the Muslims in running the life in the world to the eternal life in the afterlife.
To celebrate the Night descending of Al-Quran, on this night (17 ramadan) in Indonesia usually in a discourse or special reviewing with the theme Nuzulul Qur'an.