Fajr

The Fajr prayer (Arabic: صلاة الفجر‎‎ ṣalāt al-faǧr, "dawn prayer") is the 2 raka'at obligatory prayer ('Subuh' prayer) of the five daily prayers offered by practising Muslims. (Fajr means dawn in the Arabic language.) The five daily prayers collectively form one pillar of the Five Pillars of Islam, in Sunni Islam, and one of the ten Practices of the Religion (Furū al-Dīn) according to Shia Islam.

The Fajr prayer is mentioned by name in the Qur'an at sura 24 (An-Nur) ayah. Inspired by the tafsir of the two hadiths that were transmitted on behalf of the Islamic prophet Muhammad, the worth of the Fajr daily prayer is explained as being God's most-favoured prayer since others are asleep.

Subuh prayer requires two fard rakaʿāt. In a congregation, the leader of the prayer (imam) recites aloud. However, two sunnah rakaʿāt prior to the two Fard rakaʿāt are highly recommended and should not be missed.

The time period within which the Fajr daily prayer must be offered (with loud recitation of the quran) is from the beginning of dawn to sunrise.

The call to Fajr prayer marks the beginning of the obligatory daily fasting (sawm) during the Muslim holy month of Ramadan. The Qur'an relates a sura, Al-Fajr, by the same name.

...
Wikipedia