The Day of Ashura is on the 10th day of Muharram in the Islamic calendar and marks the climax of the Mourning of Muharram. The root for the word ashura has the meaning of tenth in Semitic languages, hence the name of the remembrance, literally translated, means "the tenth day". According to the orientalist A.J. Wensinck, the name is derived from the Hebrew asor, with the Aramaic determinative ending. The day is indeed the tenth day of the month, although some Islamic scholars offer up different etymologies.

In his book Ghuniyatut Talibin, Sheikh Abdul Qadir Jilani writes that the Islamic scholars have a difference of opinion as to why this day is known as Ashura, with some scholars suggesting that this day is the tenth most important day that God has blessed Muslims with.

In some Shi'a regions of Muslim countries such as Afghanistan, Iran, Turkey, Azerbaijan, Iraq, Lebanon, Bahrain, and Pakistan, the Commemoration of Husayn ibn Ali has become a national holiday and most ethnic and religious communities participate in it. Even in predominantly Hindu majority but secular country like India, Ashura (10th day in the month of Muharram) is a public holiday.

Ashura is a religious observance marked every year by Muslims.