A surah is the equivalent of "chapter" in the Quran. There are 114 surahs in the Quran, each divided into ayahs (verses). The chapters or surahs are of unequal length; the shortest surah (Al-Kawthar) has only three verses while the longest (Al-Baqara) contains 286 verses. Of the 114 chapters in the Quran, 86 are classified as Meccan, while 28 are Medinan. This classification is only approximate in regard to the location of revelation; any chapter revealed after migration of Muhammad to Medina (Hijrah) is termed Medinan and any revealed before that event is termed Meccan. The Meccan chapters generally deal with faith and scenes of the Hereafter while the Medinan chapters are more concerned with organizing the social life of the nascent Muslim community and leading Muslims to the goal of Dar al-Islam by showing strength towards the unbelievers. Except for surah At-Tawbah, all chapters or surahs commence with "In the Name of Allah, Ar-Rahman, Ar-Rahim ". This formula is known as the Bismillah and denotes the boundaries between chapters. The chapters are arranged roughly in order of descending size; therefore the arrangement of the Quran is neither chronological nor thematic. Surahs (chapters) are recited during the standing portions (Qiyam) of Muslim prayers. Surah Al-Fatiha, the first chapter of the Quran, is recited in every unit of prayer and some units of prayer also involve recitation of all or part of any other surah.
