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.A number of verses are associated with particular events which helps date them.
Neal Robinson, a scholar of Islamic studies, is of the opinion that there is no evidence that the style of Quran has changed in a consistent way and therefore style may not always be a reliable indicator of when and where a chapter was revealed.
According to Robinson, the problem of the chronology of authorship is still far from solved.
Except for Surah At-Tawba, all chapters or surahs commence with 'In the Name of God, the Merciful, the Compassionate'.
This formula is known as the Bismillah and denotes the boundaries between chapters.
Muhammad's last pilgrimage is mentioned in 5:3 which occurred in 632, a few months before he died.
This method is of limited usefulness because the Quran narrates the life of Muhammad or the early history of the Muslim community only incidentally and not in detail.
According to Nöldeke, earlier chapters have common features: many of them open with oaths in which God swears by cosmic phenomena, they have common themes (including eschatology, creation, piety, authentication of Muhammad's mission and refutation of the charges against Muhammad), and some Meccan chapters have a clear 'tripartite' structure (for example chapters 45, 37, 26, 15, 21).
Tripartite chapters open with a short warning, followed by one or more narratives about unbelievers, and finally address contemporaries of Muhammad and invite them to Islam.
The verses and chapters when revealed to Muhammad in the Quran did not come with a title attached to them.