Ramadan is the holiest month in Islam, during which Muslims abstain from eating and drinking from sunrise until sunset. 

The start of the month is determined by the sighting of the crescent moon, which marks the beginning of the Islamic lunar month. Countries rely on the testimonies of moon-sighters and astronomical calculation to determine the start of Ramadan.

This year, the first day of fasting is expected to be Saturday, March 1, subject to the sighting of the new moon in different parts of the world.

The Islamic calendar —the Hijri calendar — is based on the moon's cycles, varying from 29 to 30 days. This is unlike the Gregorian calendar, which is based on the solar year. As a result, the start and end of Ramadan can vary by a day or two each year.

Once the crescent moon is sighted, Muslims mark it as the start of Ramadan and their month-long fast.

The end of Ramadan is again marked by the sighting of the next crescent moon, which signals the beginning of Eid al Fitr, one of the two big festivals of Muslims. This is a time of celebration, with feasting, charity, gift-giving, and socialising with family and friends.

Why different dates? 

There are two views on the determination of the new moon in Islamic jurisprudence – those who believe Ramadan must be determined by the visibility of the new crescent by the naked eye and those who believe scientific measurement and calculations are enough. 

By using advanced technology and scientific measurement, it can be known when the crescent will be formed. On the other hand, visibility of the new crescent by the naked is only possible 8-10 hours after the crescent is formed.

Currently, many countries like Türkiye determine the month based on technology and scientific calculation, while others like Saudi Arabia, Bangladesh, Pakistan and India determine it based on visibility by the naked eye.

However, Islamic scholars have stated that both ways of moon sighting are permissible and that people should act according to their local situations.