Different communities follow different protocols for determining when a new month begins. Some communities follow a set lunar calendar, others use scientific observations to make an official decree about the arrival of a new moon, and still, others mark a new month only after the actual sighting of the crescent moon in their community.

Though the exact dates of Ramadan are never uniform around the world, they come pretty close.

Ramadan comes at a different time every year because it is the ninth month of the Islamic calendar, a date-keeping system based on lunar cycles, unlike the Gregorian calendar (the one used by most of the world, including the U.S.), which is based on the solar year