This type of calendar, which is often called as Hijiri or Muslim calendar, is actually the only left lunar calendar, which is being widely used not only for celebrations or religious purposes, but for everyday life too. Islamic calendar as Gregorian one has 12 lunar months and 354 or 255 days a year (depending on the current lunar year), it is being used by all Muslims throughout the world to know the dates of holy days and days of festivals and celebrations. The first year is called Hijira, it begun when the Muhammad phophet emigrated to Medina from Mecca. Current year of Islamic lunar calendar is 1431.

There are twelve months in the Muslim calendar, but the month Ramadan is the most widely known and holy one, during this period Muslims are keeping the holy post – they do not perform any sexual activity, eat, or drink during the daylight for the whole month.

The Hijiri calendar system is very significant and has a great influence on most Muslim believer's lives, but it is being decreasing in modern times - the Islamic calendar is mostly used only to determine the correct starting date of Ramadan and dates of religious holidays. Unfortunately, as this calendar is fully a lunar one – this means it cannot be used for governmental or agricultural purposes. Since ancient times, Muslims had alternative calendar versions for above mentioned purposes.