Mharram (Arabic: محرم) is the first month of the Islamic calendar. It is one of the four sacred months of the year in which fighting is prohibited. Since the Islamic calendar is lunar, Muharram moves from year to year when compared with the Gregorian calendar. Muharram is so called because it is unlawful to fight during this month; the word is derived from the word haram, meaning "forbidden". It is held to be the most sacred of all the months, excluding Ramadan. Some Muslims fast during these days. The tenth day of Muharram is called Yaumu-l 'Ashurah, which is known by Shia Muslims as ‘the day of grief’. Fasting differs among the Muslim groupings; mainstream Shia Muslims stop eating and drinking during sunlight hours and do not eat until late afternoon. Sunni Muslims also fast during Muharram for the first 10 days of Muharram or on the tenth day or on both the 9th and 10th days, the choice is upto the individual. Shia Muslims do so to replicate the sufferings of Imam Hussain (A.S) on the day of Ashurah.
The word "Muharram" is often considered synonymous with the event of Ashura. Ashura, which literally means the "Tenth" in Arabic, refers to the tenth day of Muharram. It is well-known because of historical significance and mourning for the martyrdom of Husayn ibn Ali ,
The shias start the mourning from the 1st night of Muharram which continues for 2 months and 8 days. However the first days are the most important since these were the days where Imam Hussain and his family/followers were put through to atrocities by Yazeed. Imam Hussain and his group of 72 people consisting of women, children and aged.
The day Ashura stands for the war between good and evil. Between right and wrong. Between the true Islam and the Islam which the perpetrators like Yazeed and Shimr wanted. Yazeed had become very powerful back in 60 Hijri and was spreading the Islam of atrocities, killings and other heinous acts. However when he asked Imam Hussain son (A.S) of Imam Ali (A.S.) and grandson of Prophet Mohammed (S.A.W.S), the answer was a straight no. This is the reason why Yazeed sent a large of 1000s to wage a war against a mere 72.
From the 7th Muharram itelf Umar ibn Sa'ad (Commander of Yazeed's army) stopped all the supplies of water and by this time the food supplies had also finished. On the day of Ashura they waged a war against Imam Hussain and Imam Hussain's group fought a very brave battle with the Yazeeds army. Thus mourning is done in remembrance of Imam Hussain and his family, not because they lost their lives but they were put through torture and hell. Even Imam Hussains (A.S) 6 month son Ali Asghar was not spared and when was brought out in the daylight, was killed by Shimr Ibn Thil-Jawshan(Soldier in the Ummayad).