Their daylight hours will be spent without any food, water, smoking and sex. Last year, fasting hours around the world ranged between 9 and 21 hours. This year, fasting hours will range between 9 and 19 hours – with fasting more difficult for those living in countries in the far north, where the sun can remain in the sky almost all day.
Acts of worship that increase in Ramadan include reading the Quran and night prayers called taraweeh.
Muslims around the world make their way to mosques after their iftar and spend the evening in prayer together in large groups.
On Wednesday night, masses of worshippers performed their first taraweeh prayers globally to mark the first night of the holy month.
See some of them in pictures here: