The starting and ending time of fasting is from dawn to sunset in the east every day. During this period, people who fast should abstain from eating, drinking and having sex.

There are two ways to shine in the east: true light and false light. False light is straight light (vertical light).

That is, just after dawn in the east, a light appeared on the horizon. Both sides of the light are black. True brightness is horizontal brightness. That is, there is a light on the eastern horizon, and the scope of light is larger. True light is usually ten minutes after false light. The time when people who fast stop eating really shows now, and then they can't fast if they eat and drink again. You have to make up for one more day of fasting.

Extended data:

The prophet Muhammad of Islam stipulated fasting in August the following year after he moved from Mecca to Medina. According to the Islamic calendar, September (Ramadan) is the month of fasting for Christians. September was chosen as Ramadan because "in Ramadan (September), God began to reveal the Koran to guide the world and show clear evidence so as to follow the right path and distinguish the true from the false."

The earliest Islamic Ramadan law began in 623 AD. This is described in detail in 183, 184, 185 and 187 in the second chapter of the Koran. Muhammad, the messenger of Allah, also said: "Ramadan is the month of Allah, which is more expensive than any month of the year."