Is the Night of Decree a specific period, or does it last the entire night, and is it sufficient to observe it for an hour, or must one pray throughout it completely?

Laylat al-Qadr encompasses the entire night, from sunset until the true dawn. Its observance is achieved by performing even a little bit of tahajjud, or by praying tarawih with the Imam, or by praying Isha and Fajr in congregation. This is based on the Prophet's (peace be upon him) saying: “Whoever prays Isha in congregation is as if he has spent half the night in prayer, and whoever prays Fajr in congregation is as if he has prayed the entire night.” Forgiveness is attained by observing it, even if the person does not know its exact time, as long as their intention in observing it is to seek it.