Explanation

It is based on a year of 12 months: Muḥarram, Ṣafar, Rabīʿ al-Awwal, Rabīʿ al-Thānī, Jumādā al-Awwal, Jumādā al-Thānī, Rajab, Shaʿbān, Ramaḍān (the month of fasting), Shawwāl, Dhū al-Qaʿdah, and Dhū al-Ḥijjah. Each month begins approximately at the time of the new moon.