The reason for naming the Hijri calendar
This name was given to the Hijri calendar in reference to the migration of the Messenger of God – Muhammad, may God bless him and grant him peace – from Mecca to Medina, and the year in which he migrated was adopted as the first year of migration. It is a lunar calendar that relies on the sighting of the moon to determine the beginnings and ends of all months, and the name of the Arab calendar or the Islamic calendar is also given to this calendar.
Number of days in the Hijri calendar
The number of days in the Hijri lunar calendar is 255 days, which is the time it takes for the moon to complete a full cycle, and these days are distributed over 12 months, but the number of days is not necessarily the same every year, which means that the number of days in a month may increase or decrease by one day between one year and another because the number of days in the month is 29 days or 30 days according to the result of the crescent sighting.