Why is 17 Ramadan Seen as the Time of the Qur'an's Descent (Nuzul al-Qur'an)?

The Qur’an is the word (kalam) of Allah revealed to the Prophet Muhammad (SAW) through the Angel Jibril, with its wording and meaning. As Allah’s book, the Qur’an occupies the position of the primary and first source of all Islamic teachings.

Linguistically, the Qur’an derives from Arabic meaning ‘a recitation’ or ‘something that is read repeatedly.’ The Qur’an is a noun (masdar) from the verb qara’a meaning ‘to read.’

The use of this term is also found in Surah al-Qiyamah, verses 17-18. It means, ‘Indeed, We will gather it (in your chest) and cause you to recite it (wa qur`aanah). When We have finished reciting it, then follow its recitation.’

This Book of Allah has several names, not only Qur’an. This is evident in several verses. Among its names are al-Kitab, al-Furqan (the differentiator of truth from falsehood), adz-Dzikr (the admonition), al-Mau’idhah (the lesson), and al-Hukm (the ruling).

In Islamic tradition, the descent (revelation) of the Qur’an is first referred to as Nuzulul Qur’an. Usually, the commemoration of Nuzulul Qur’an takes place on the 17th of Ramadan. In Indonesia, on that date it is often celebrated with a range of activities, such as tadarus of the Qur’an or religious studies.

Why do Muslims generally observe the ‘night of the Qur’an’s descent’ on 17 Ramadan, while in the Qur’an itself—specifically Surah al-Qadr—it is stated that Allah revealed this Kalam on the Night of Decree (Lailatul Qadar)?