Ashura is commemorated by Muslims as a day of mourning for the martyrdom of Imam Hussain ibn Ali, the grandson of Prophet Muhammad (PBUH) at the Battle of Karbala on 10 Muharram in the year 61 AH.
The massacre of Imam Hussain with small group of his companions and family members had great impact on the religious conscience of Muslims. The day has ever been remembered sorrow and passion.
In Afghanistan, Iran, Iraq, Lebanon, Bahrain, and Pakistan, the commemoration of Imam Hussain has become a national holiday.
Even in a predominantly Hindu majority but secular country like India, Ashura (10th day in the month of Muharram) 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).
Ashura October 23-24