Ramadan, the most important month of the year in the Muslim calendar, begins Sunday. For Muslims, the monthlong celebration commemorates Allah, the Arabic name for God, giving the first verses of the Quran, the Muslim holy book, to the Prophet Muhammad in the year 610 A.D.

For 30 days, Muslims around the world do not eat from dawn to dusk, pray intensely and gather for nightly feasts to break the fast.

Observing Ramadan is one of the Five Pillars of Islam, the five duties that are obligatory for every Muslim.