Literally, Ṣawm means ‘to abstain’. In the terminology of Islamic law, Ṣawm means to abstain from eating, drinking and sexual intercourse; with the conditions that one abstains continuously from dawn to sunset, and that there is an intention to fast. Therefore, should one eat or drink anything even a minute before sunset, the fast will not be valid. Similarly, if one abstained from all these things throughout the day but made no intention to fast, there will be no fast too.

Ṣawm or ‘fasting’ is an ʿibādah, an act of worship in Islām, regarded as its pillar and sign.

As far as the merit of this month is concerned, it has been said that Allāh has chosen this month to reveal Scriptures. Consequently, the Qurʾān was revealed in this very month. According to a narration from the Companion Ḥaḍrat Wāthilah ibn Asqaʿ رضي الله عنه appearing in the Musnad of Aḥmad, the Prophet ﷺ said that Abrahamic scriptures were revealed on 1st Ramaḍān, the Torāh on the 6th, the Evangel on the 13th and the Qurʾān on the 24th of Ramaḍān. In another narration from the blessed Companion Ḥaḍrat Jābir رضي الله عنه, it appears that Zabūr (Psalms) was revealed on the 12th of Ramaḍān and the Evangel on the 18th. [Ibn Kathīr]

All previous Books mentioned in the Ḥadīth cited above were revealed on dates given in their entirety. It is a peculiarity of the Qurʾān that it was sent from the Preserved Tablet down to the Firmament of the Earth in one night of the month of Ramaḍān, all of it. But it was revealed to the Prophet ﷺ gradually during a period of 23 years.

[Maʿāriful Qurʾān, Volume 1, Page 453 – 459]