The fasting is designed as a spiritual effort, a struggle against the seduction of earthly pleasures. What is Ramadan? How does it take place? Who is concerned? How is the date determined? Nearly one and a half billion Muslims in the world Monday began the month of fasting and sacred prayers of Ramadan, which commemorates the divine revelation received by the Prophet Muhammad (PBUH). What is Ramadan? Ramadan is one of the five pillars of Islam, with the profession of faith, the obligation to pray five times a day, almsgiving and pilgrimage to Mecca. It represents, for Muslims, a month of piety, charity and frugality. How does it take place? During this period, which lasts 29 or 30 days, believers abstain from eating, drinking, smoking and having sex, from sunrise to sunset. This fasting is designed as a spiritual effort, a struggle against the seduction of earthly pleasures. But at the time of the daily breaking of the fast, festive meals traditionally gather families and social activity is intense. The end of Ramadan feast, Eid al-Fitr, is celebrated with pomp, often with family. Who is concerned? Respect of fasting is imposed on all believers who have passed the age of puberty. Even if children are exempted, it is recommended that they are taught gradually. Pregnant women or nursing mothers, the sick, travelers and fighters have the right not to fast, but the duty to submit to it as soon as they are again in a position to do so. Ramadan may be particularly challenging this year for many practitioners as it takes place during the period when the days are longer and temperatures are very high in most Muslim countries. How is the date of Ramadan determined? Ramadan is the ninth month of the Hijri calendar, which Muslims refer to their religious festivals and is based on the lunar cycle. This calendar has eleven days shorter than the solar calendar, for this reason, the dates of beginning and end of Ramadan vary each year. The first day is determined throughout the "night of the doubt" during which we observe the emergence of the first quarter of the new moon, which must be visible to the naked eye and duly established. Theologians, scholars and religious therefore meet annually to set the precise time, which varies from different locations. Messaoud Oudina