Palestinians read copies of the Koran, Islam's holiest book, on the first day of fasting in the Muslim holy month of Ramadan, at the al-Omari mosque in Gaza City, on May 27, 2017. Ramadan is sacred to Muslims because it is during that month that tradition says the Koran was revealed to the Prophet Mohammed. The fast is one of the five main religious obligations under Islam. More than 1.5 billion Muslims around the world will mark the month, during which believers abstain from eating, drinking, smoking and having sex from dawn until sunset. Photo by Ashraf Amra