The Surah has been so named after the very first word at-tin.
According to Qatadah, this Surah is Madani. Two different views have been reported from Ibn Abbas: first that it is a Makki Surah, and second that it is Madani. But the majority of scholars regard it as a Makki revelation, a manifest symbol of which is the use of the words hadh-al-balad-il-amin (this city of peace) for Makkah. Obviously, if it had been revealed at Madinah, it would not be correct to use the words "this city" for Makkah Besides, a study of the contents of the Surah shows that it belongs to the earliest period of Makkah, for in it there is no sign whatever to indicate that during the period of its revelation any conflict had started between Islam and unbelief. Moreover, it reflects the same style of the earliest revelations of Makkah period in which briefly and succinctly the people have been made to realize that the judgment of the Hereafter is necessary and absolutely rational.
Its theme is the rewards and punishments of the Hereafter. For this purpose first swearing an oath by the habitats of some illustrious Prophets, it has been stated that Allah has created man in the most excellent of molds. Although at other places in the Quran, this truth has been expressed in different ways, for example, at some places it has been said: "Allah appointed man His vicegerent on the earth and commanded the angels to bow down to him (Al-Baqarah: 30,34, Al-Anam: 165, Al-Araf: 11, Al-Hijr 28,29, An-Naml: 62, Suad 71- 73);" at others that: "Man has become bearer of the Divine trust, which the earth and the heavens and the mountains did not have the power to bear (Al-Ahzab 72);" and at still others that: "We honored the children of Adam and exalted them above many of Our other creatures (Bani Israil 70)," yet here the statement made on oath in particular by the habitats of the Prophets that man has been created in the finest of molds, signifies that mankind has been blessed with such an excellent mold and nature that it gave birth to men capable of attaining to the highest position of Prophethood, a higher position than which has not been attained by any other creature of God.
Then, it has been stated that there are two kinds of men. those who in spite of having been created in the finest of molds, become inclined to evil and their moral degeneration causes them to be reduced to the lowest of the low, and those who by adopting the way of faith and righteousness remain secure from the degeneration and consistent with the noble position, which is the necessary demand of their having been created in the best of molds. The existence among mankind of both these kinds of men is such a factual thing which no one can deny, for it is being observed and experienced in society everywhere at all times.
In conclusion, this factual reality has been used as an argument to prove that when among the people there are these two separate and quite distinct kinds, how can one deny the judgment and retribution for deeds If the morally degraded are not punished and the morally pure and exalted are not rewarded and both end in the dust alike, it would mean that there is no justice in the Kingdom of God; whereas human nature and common sense demand that a judge should do justice. How then can one conceive that Allah, Who is the most just of all judges, would not do justice?
Source: Sayyid Abul Ala Maududi - Tafhim al-Qur'an - The Meaning of the Quran