Sawm (ie. fasting) is the third pillar of lslam.
All adult Muslims must abstain from eating, drinking and intimate relations with their spouses from dawn (Subh Saadiq) to sunset (Maghrib), during the days of Ramadaan (the ninth month of the Islamic calendar).
Those who are travelling or sickly can defer fasting during Ramadaan, and make up for the missed fasts later.
Children may fast too if they wish, but it is not compulsory upon them.
The purpose of Sawm is to:
…develop piety and god-consciousness.
…gain Allah’s pleasure & closeness to Him.
…gain the eternal rewards of Jannah.
…gain protection from the fire of Jahannam
…discourage Muslims from committing evil.
…remove sin and cleanse the heart.
…enlighten the thoughts and ideas of a Muslim.
…develop self-control and overcome greed, selfishness, laziness & other weaknesses.
…develop compassion & solidarity with others, in particular the poor.