Nuzulul Qur'an which literally means the descent of the Qur'an is a term that refers to the important events of the decline of the Qur'an as a whole descended from Lauhul Mahfuzh to Baitul 'Izzah in the sky of the world.
The Qur'an was passed down gradually to the Messenger of Allah (peace and blessings of Allaah be upon him) according to the events of a period of about 23 years.
Believed this Nuzulul Quran event on the night of 17 Ramadan.
شَهْرُ رَمَضَانَ الَّذِي أُنْزِلَ فِيهِ الْقُرْآَنُ هُدًى لِلنَّاسِ وَبَيِّنَاتٍ مِنَ الْهُدَى وَالْفُرْقَانِ. البقرة 185
The month of Ramadan, the moon in which it is revealed (beginning) of the Qur'an as a guide for man and the explanations of the guidance and the distinction (between the right and the vanity). "(Surat al-Baqarah: 185)