The Hijri calendar, or Arabic calendar also known in English as the Muslim calendar and Islamic 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 fasting and the annual season for the great pilgrimage. In almost all countries where the predominant religion is Islam, the civil calendar is the Gregorian calendar, with Syriac month-names used in the Levant and Mesopotamia but the religious calendar is the Hijri one.
Islamic calendar stamp issued at King Khalid International Airport on 10 Rajab 1428 AH (24 July 2007 CE)
Illustration of Muhammad prohibiting Nasī'. Found in an illustrated copy of Al-Biruni's The Remaining Signs of Past Centuries (17th-century copy of an early 14th-century Ilkhanid manuscript).
Muslim clerics observe the moon.
Civil and Hijri establishment dates of a library in Old City, Jerusalem
Arabic is a Central Semitic language of the Afroasiatic language family spoken primarily in the Arab world. The ISO assigns language codes to 32 varieties of Arabic, including its standard form of Literary Arabic, known as Modern Standard Arabic, which is derived from Classical Arabic. This distinction exists primarily among Western linguists; Arabic speakers themselves generally do not distinguish between Modern Standard Arabic and Classical Arabic, but rather refer to both as al-ʿarabiyyatu l-fuṣḥā or simply al-fuṣḥā (اَلْفُصْحَىٰ).
Safaitic inscription
The Namara inscription, a sample of Nabataean script, considered a direct precursor of Arabic script.
Arabic from the Quran in the old Hijazi dialect (Hijazi script, 7th century AD)
The Qur'an has served and continues to serve as a fundamental reference for Arabic. (Maghrebi Kufic script, Blue Qur'an, 9th–10th century)