The martyrdom of Husayn is commemorated annually through the first ten days of Muharram, culminating on Ashura. The observances, the recitation of the passion in gatherings called majalis, the lamentation and weeping, the processions, the passion plays known in Iran as ta'ziyeh, and in some communities acts of ritual mourning upon the body, constitute one of the most emotionally intense devotional cycles in any religion, and they are living practice for the world's Shia today.
The Arba'in pilgrimage, forty days after Ashura, draws many millions on foot to Husayn's shrine at Karbala, among the largest annual gatherings of humanity anywhere.
The meaning of Karbala has also travelled beyond the Shia community and beyond Islam. Husayn's stand became, for many, a universal emblem of principled resistance to injustice: figures as distant as Mahatma Gandhi invoked his example, and the theme of a righteous few against an unjust power has resonated widely. Within Islam the day is marked by Sunnis too, though differently, as a day of fasting associated in Sunni tradition with the deliverance of Moses, so that Ashura carries distinct meanings across the branches. For Shia Islam, however, it is above all the day of Husayn.