Sunnah
Muslims often pray extra prayers on this day, particularly the night prayer. They awake, pray, and hope God will give them anything they may desire on this night. Mostly, they perform tilawat (reading the Quran).
Those who can afford to devote their time in the remembrance of God stay in the mosque for the final ten days of Ramadan. This worship is called Iʿtikāf (retreat). They observe a fast during the day and occupy themselves with the remembrance of God, performing voluntary prayers and studying the Quran, day and night, apart from the obligatory prayers which they perform with the congregation. Food and other necessities of life are provided for them during their stay in the mosque. Devoting time to remember God, Muslims also hope to receive divine favors and blessings connected with Lailat ul-Qadr.
As per the Quran (Sure Qadr) Angels come down on the earth with all things (destiny of the people for the coming year). "The angels and Jibreel descend in it by the permission of their Lord for every affair" (97:4)
Read more about this topic: Laylat Al-Qadr