Muslims around the world from Indonesia to Dearborn, Michigan, to Tajikistan are preparing for the start of the holy month of Ramadan. Vendors in large markets in Pakistan are selling dates with which to break the fast, and lights have been hung across streets in Cairo.

Ramadan’s start date changes every year because Islam uses a lunar calendar and the holiday always falls during the calendar’s ninth month. Scholars believe the Quran, the holy text in Islam, was first revealed during the ninth month. During Ramadan many people read and recite passages from the holy book.

Moon sighting committees in Saudi Arabia and the United Arab Emirates will meet Sunday evening to look for the Crescent moon and determine the exact start date of the holy fasting month, probably Monday. Lunar months are shorter, which accounts for the date moving back each year by several days.

For the world’s more than 1.6 billion Muslims, Ramadan marks a period of fasting from dawn until dusk (including abstaining from both water and food), prayer and alms giving. Fasting, alms giving and prayers are all part of the five pillars of the Islamic faith.

Ramadan Muslims are preparing for Islam's holy month of Ramadan, which is calculated on the sighting of the new moon, and during which they fast from dawn until dusk. Pictured: A Pakistani vendor arranges dates at a market ahead of the Islamic holy month of Ramadan in Peshawar, June 2, 2016. Photo: A MAJEED/AFP/Getty Images

Those taking part in fasting often wake up around 4 a.m. or 5 a.m. to eat and drink ahead of their daylong fast. At sundown, the daily fast is broken with the iftar meal, which usually consists of dates, sweet drinks and desserts. During long summer days this year, fasting could last as many as 17 hours a day, the Independent reported.

Many Muslims begin taking part in Ramadan once they have turned 12 years of age. Fasting serves as a reminder of those less fortunate around the globe and builds a connection with Allah.

Ramadan ends each year at the beginning of Shawwal, the 10th month of the Islamic calendar, which will likely fall on either July 4 or 5. A major feast known as Eid al-Fitr marks the end of Ramadan. Fireworks, festivities and large meals are part of the festivities around the globe.