The Islamic calendar (Arabic: ٱلتَّقْوِيم ٱلْهِجْرِيّ at-taqwīm al-hijrīy), also known as the Hijri, Lunar Hijri, Muslim or Arabic calendar, is a lunar calendar consisting of 12 lunar months in a year of 354 or 355 days. It is used to determine the proper days of Islamic holidays and rituals, such as the annual period of fasting and the proper time for the Hajj. The civil calendar of almost all countries where the religion is predominantly Muslim is the Gregorian calendar, with Syriac month-names used in the Levant and Mesopotamia (Iraq, Syria, Jordan, Lebanon and Palestine). Notable exceptions to this rule are Iran and Afghanistan, which use the Solar Hijri calendar. Rents, wages and similar regular commitments are generally paid by the civil calendar.
