The Islamic calendar, also called the Hijri calendar, is used in many parts of the Muslim world either in replace of or along with the Gregorian calendar. The Islamic calendar is based on 12 months and follows the lunar system. The names of these months are Muḥarram, Ṣafar, Rabīʿ al-Awwal, Rabīʿ al-Thānī, Jumādā al-Awwal, Jumādā al-Thānī, Rajab, Shaʿbān, Ramadan (the month of fasting), Shawwāl, Dhū al-Qaʿdah, and Dhū al-Ḥijjah.
Because the Islamic calendar is based on the lunar system, each month begins with the sighting of the new moon. Therefore, the months are either 29 or 30 days. Therefore, the Islamic calendar year has less days than the Gregorian calendar. As a result, the months shift about 10 days every year in comparison to the Gregorian calendar. For example, if Ramadan starts on April 10 this year, the following year it will start on April 1st. Each year it will keep shifting until it makes a full cycle. There are no leap days intercalated, so that the Islamic months do not remain in the same seasons but retrogress through the Gregorian calendar over a period of about 32.5 years.
The Islamic calendar is called the Hijri calendar because it is based on the Hijra (migration) of the Prophet Muhammad peace be upon him from Mecca to Medina. Before the Islamic empire expanded, early Muslims used major events to determine years. For example, they had the year of the elephant in which an army from Yemen riding elephants attacked Mecca to destroy the Kaba. After the death of the Prophet Muhammad peace be upon him, the Islamic empire expanded, and the Muslims recognized that they needed a calendar. They gathered to decide a start date for the calendar and came to a consensus that the migration of the Prophet Muhammad peace be upon him from Mecca to Medina was the best start date.
They decided this for several years, chief among them is the fact that it was after the migration that Muslims were able to practice Islam publicly without persecution. Therefore, the calendar is sometimes distinguished with the initials AH, meaning “after hijra.” The Islamic months are listed below along with some major events and holidays in these months.
The first month of the Islamic calendar. Ashura falls on the 10th of Muharram and some Muslims voluntarily fast on that day. It also marks the unjust murder of Hussein; the grandson of the Prophet Muhammad peace be upon him.
The month in which the Prophet Muhammad peace be upon him was born, died. It is also the month in which the Prophet migrated from Mecca to Medina.
The month in which the Holy Qur’an started to be revealed and the month in which the Muslims fast from sunrise to sunset.
On the first day of this month Eid al-Fitr is celebrated.
The month in which the Hajj is performed and Eid al-Adha is celebrated on the 10th of this month.