I'tikaf is confining or secluding oneself for private devotions in a Masjid starting on the evening (a little before sunset) on the 20th day of Ramadhan until the sighting of the Eid moon.
Going out of the Masjid during I'tikaf is not permitted except for necessary purposes. During I'tikaf spend time in prayer, reading Qur'an, study circles, and making Du'a.
The blessed Prophet (peace be upon him) used to perform I'tikaf annually. The minimum duration of I'tikaf is one day and one night.
The night prayers are Sunnah. They can be done at any time during the night (about mid night up until Fajr). They are performed as a series of two Rak'a.
It is recommended to sleep for part of the night before getting up to do Tahajjud and then to sleep again afterwards until Fajr time.
It is encouraged for those spending their time in practicing the I'tikaf to pray Tahajjud. It can be prayed individually or in congregation.
Layla-tul-Qadr (Night of Power)
A night which is better than a thousand months. It is mentioned in the Qur'an (44:3 & Surah 97) as being the night in which the Qur'an was sent down to this world.
Aisha (Allah be pleased with her) related that Rasulullah (peace be upon him) said,
"Look for Layla-tul-Qadr on an odd numbered day during the last ten nights of Ramadhan." (Bukhari)
For that reason, many perform I'tikaf and stay up all night seeking their Lords forgiveness and guidance.