Ramadan

Ramadan [is] the ninth month of the Muslim calendar and the holy month of fasting. It begins and ends with the appearance of the crescent moon. Because the Muslim calendar year is shorter than the Gregorian calendar year, Ramadan begins 10–12 days earlier each year, allowing it to fall in every season throughout a 33-year cycle. Ramadan lasts from Saturday, April 2 to Sunday, May 1 in 2022. (Dates are dependent on the appearance of the crescent moon and may vary across countries.)

Encyclopaedia Britannica