Muharram (Arabic: المحرّم) is the first month of the Islamic calendar. It is one of the four sacred months of the year.^[1] Since the Islamic calendar is a lunar calendar, Muharram moves from year to year when compared with the Gregorian calendar.

The word "Muharram" means "Forbidden" and is derived from the word harām, meaning "sinful". It is held to be the most sacred of all the months, excluding Ramadan. Some Muslims fast during these days. The tenth day of Muharram is the Day of Ashura, which to Shia Muslims is part of the Mourning of Muharram.

Some Muslims fast during this day, because it is recorded in the hadith^[2] that Musa (Moses) and his people obtained a victory over the Egyptian Pharaoh on the 10th day of Muharram; accordingly Muhammad asked Muslims to pray on this day that is Ashura and on a day before that is 9th (called Tasu`a).

Fasting differs among the Muslim groupings; many Shia Muslims stop eating and drinking during sunlight hours and do not eat until late afternoon. Sunni Muslims also fast during Muharram for the first ten days of Muharram, or just the tenth day, or on both the ninth and tenth days; the exact term depends on the individual. Shia Muslims do so to commemorate the martyrdom of Hussein ibn Ali on the Day of Ashura.