For Shia Muslims, Ashura, the tenth day of Muharram, marks the climax of the Remembrance of Muharram, and commemorates the martyrdom of Hossein ibn Ali, the grandson of Muhammad (PBUH) at the Battle of Karbala on 10 Muharram in the year 61 AH ( October 10, 680 CE). This year Ashura falls on Oct 12.
The massacre of Imam Hossein with a small group of his companions and family members had a great impact on the religious conscience of Muslims, particularly Shia Muslims, who commemorate his martyrdom with sorrow and passion.
Mourning for Imam Hossein and his companions began almost immediately after the Battle of Karbala by his surviving relatives and supporters.
Performing Ta'ziyeh (mourning theater) and cooking various kinds of food called (Nazri in Persian culture, or charity food) and distributing it among other people for free, are among the main parts of the ritual.
The ninth and tenth (also known as Ashura) days of Moharram are the climax of a ten-day mourning ritual, which is performed in commemoration of the third Shia Muslim's Imam and his troops in the battle of Karbala.
In Tasu'a and Ashura, Iranian Muslims, along with others from around the world, in a sign of unity come to the street and mark the days and send the message to the world that they will not surrender to the oppression of any power, no matter how big it is.
In Iran, Afghanistan, Iraq, Lebanon, Bahrain, and Pakistan, the commemoration of Imam Hossein has become a national holiday and most ethnic and religious communities participate in it. In India, Ashura is a public holiday due to the presence of a significant Indian Shia Muslim population (2-3% of total population, 20-25% of Indian Muslim population).