The Festival of Muharram (Arabic: احتفال محرم or مناسبة محرم) is an important period of mourning in the Shi'ite branch of Islam. It signifies the Karbala tragedy when Husayn bin Ali, a grandson of Muhammad, was martyred. Muharram is the first month of Islamic lunar calender. This marks the time when Prophet Muhammed was driven out of Mecca. He, along with Muslims, took refuge in the city Ya-Th'rib, which was later renamed to Medina (City of Prophet). Though Muslims around the world celebrate the new Islamic year, the Shi'ite sect has most visible celebration proceedings.

This festival is observed in the first month of the Hijra year, Muharram. Mourners, both male and female, congregate together (in separate sections) for sorrowful, poetic recitations performed in memory of the martyrdom of Imam Husayn, lamenting and grieving to the tune of beating drums and chants of "Ya Husayn." Passion plays are also performed, reenacting the Battle of Karbala and the suffering and death of Husayn at the hands of Yazid.

Many of the male participants congregate together in public for ceremonial chest beating as a display of their devotion to Husayn and in remembrance of his suffering. In certain Shi'a societies, mainly Lebanon and Iraq, some male participants will inflict actual wounds upon themselves, though this practice is viewed as being extreme and is widely discouraged and banned in other countries with significant Shi'a populations, such as Iran.

For the duration of the festival, it is customary for mosques to provide free meals on certain nights of the month to all people. These meals are viewed as being special and holy, as they have been consecrated in the name of Husayn, and thus partaking of them is considered an act of communion with God, Husayn, and humanity.

It is from the traditional cry of "Ya Husayn" that the title of Hobson-Jobson, a dictionary of Hindustani terms, is derived.