Muslims across the Middle East are set to begin observing the holy month of Ramadan from Thursday, following confirmation from clerics that the crescent moon had not been visible on Tuesday night. During Ramadan, Muslims fast from dawn until dusk, not eating, drinking, smoking or having sex during daylight hours. The fast is one of the five pillars of Islam and is compulsory for healthy Muslims, but exceptions are made for those who are ill, pregnant, breastfeeding or very young. Muslims are expected to adhere to daily prayers and heightened religious contemplation throughout the month.