Laylat Al-Qadr
Sometimes referred to as "the night of power" or 'the night of decree", Laylat al-Qadr is considered the most holy night of the year. This is the night in which Muslims believe the first revelation of the Quran was sent down to Muhammad stating that this night was "better than one thousand months, as stated in Chapter 97:3 of the Qu'ran.
Also, generally, Laylat al-Qadr is believed to have occurred on an odd-numbered night during the last 10 days of Ramadan, i.e., either the night of the 21st, 23rd, 25th, 27th or 29th.
Read more about this topic: Ramadan