Muḥarram (Arabic: مُحَرَّم‎‎ muḥarram) is the first month of the Islamic calendar. It is one of the four sacred months of the year.[1]Since the Islamic calendar is a lunar calendar, Muharram moves from year to year when compared with the Gregorian calendar.

The word "Muharram" means "forbidden". It is held to be the second holiest month, following Ramadan. Some Muslims fast during these days. The tenth day of Muharram is the Day of Ashura, which to Shia Muslims is part of the Mourning of Muharram.
Sunni Muslims fast during this day, because it is recorded in the hadith[2] that Musa (Moses) and his people obtained a victory over the Egyptian Pharaoh on the 10th day of Muharram; accordingly Muhammad asked Muslims to fast on this day that is Ashura and on a day before that is 9th (called Tasu'a).

Shia Muslims during Muharram do different things and with different intentions. Shia Muslims observe and respect Muharram as the month that martyred Hussein ibn Ali, the grandson of Muhammad and son of Ali, in the Battle of Karbala. They mourn for Hussein ibn Ali and refrain from all joyous events. Unlike Sunni Muslims, Shias do not fast on the 10th day of Muharram.[3] In addition there is an important Ziyarat book, the Ziyarat Ashura about Hussein ibn Ali. In the Shia sect it is popular to read this ziyarat on the "Day of Ashura", although most of the Shias try to read Ziyarat Ashura every day and they send salutations to Hussein ibn Ali.[4] The Sufi sect and followers of Ahl al-Bayt of Sunni Muslim from India, Bangladesh and from various parts of the world reads the Noha, Marsiya and deliver lecture on Imam Hussein's life and his scarification for Islam. Muharram of Sunni peoples of Bengal-especially the Sufi and Ahl al-Bayt lovers are very well known. These Sunni sects do the mourning of Imam Hussain and his Ahl al-Bayt from the first day of Muharram till the forty days after Ashura. However, Sunni Muslims who observe these rites, along with those who revere the Ahl al-Bayt, are considered to be a minority among the Sunnis, as these are primarily Shia observances.

Muharram and Ashura
With the sighting of the new moon the Islamic New Year is ushered in. The first month, Muharram, is one of the four sacred months that Allah has mentioned in the Quran: Muharram, Rajab, Dhu al-Qi'dah, and Dhu al-Hijjah. Even before Islam came, Quraish and Arabs as a whole knew the sanctity of the months and were forbidden to wage wars on those months.
Muharram and Ashura to the Shia

Muharram is a month of remembrance and modern Shia meditation that is often considered synonymous with 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 murder of Hussein ibn Ali, the grandson of Muhammad.[3]
Shiite begin mourning from the first night of Muharram and continue for ten nights, climaxing on the 10th of Muharram, known as the Day of Ashura. The last few days up until and including the Day of Ashura are the most important because these were the days in which Imam Hussein and his family and followers (including women, children and elderly people) were deprived of water from the 7th onward and on the 10th, Imam Hussain and 72 of his followers were killed by the army of Yazid I at the Battle of Karbala on Yazid's orders. The surviving members of Imam Hussein's family and those of his followers were taken captive, marched to Damascus, and imprisoned there.
Timing
The Islamic calendar is a lunar calendar, and months begin when the first crescent of a new moon is sighted. Since the Islamic lunar calendar year is 11 to 12 days shorter than the solar year, Muharram migrates throughout the solar years. The estimated start and end dates for Muharram are as follows (based on the Umm al-Qura calendar of Saudi Arabia:[4])
AH
First day (CE / AD)
Last day (CE / AD)

1437 14 October 2015 12 November 2015
1438 2 October 2016 31 October 2016
1439 21 September 2017 20 October 2017
1440 11 September 2018 9 October 2018
1441 31 August 2019 29 September 2019
1442 20 August 2020 17 September 2020
Muharram dates between 2015 and 2020
The approximate dates for the next Muharram is from 21 September 2017 to 20 October 2017.[5][6]
Incidents occurred during this month
• 01 Muharram: anniversary of the death of Hazrat Ammasaheb Bibi Habiba Qadri in India; Birth of the Báb (forerunner of the Bahá'í Faith) in 1235 AH.
• 02 Muharram: Hussein ibn Ali enters Karbala and establishes camp. Yazid's forces are present. Birth of Bahá'u'lláh (founder of the Bahá'í Faith) in 1233 AH.
• 07 Muharram: Access to water was banned to Husayn ibn Ali by Yazid's orders.
• 10 Muharram: Referred to as the Day of Ashurah (lit. "the tenth") was the day on which Hussein ibn Ali was martyred in the Battle of Karbala. Shia Muslims spend the day in mourning, whilst the Sunni Muslims fast on this day commemorating the rescue of the people of Israel by Musa (Moses) from Pharaoh[7]
Many Sufi Muslims fast for the same reason as the Sunnis mentioned above, but also for the martyred people in Karbala, they pray for them and send upon them peace and blessings.
• 15 Muharram: Birth of Muhammad Sirajuddin Naqshbandi in 1297 AH (1879-1880 AD)
• 25 Muharram: Zayn al-‘Ābidīn, fourth Shia Imam was martyred by Marvanian in 95 AH (714 AD).[8]
• 27 Muharram, Maytham al-Tammar was martyred.
• 28 Muharram: Death anniversary Urs of Ashraf Jahangir Semnani in 808 AH (1405 AD) a great Sufi saint in India.
• Death anniversary Urs of Baba Farid, a great Sufi saint in Pakistan for six days in Muharram.
Hadith
• Abu Hurairah said that the Prophet said:
There will be an Ayah(sign) in (the month of) Ramadan. Then, there will 'isabah (splitting into groups) in Shawwal. Then, there will be fighting in (the month of) Dhu al-Qi'dah. Then, the pilgrim will be robbed in (the month of) Dhu al-Hijjah. Then, the prohibitions will be violated in (the month of) al-Muharram. Then, there will be sound in (the month of) Safar, then the tribes will conflict with each other in the two months of Rabi' al-awwal & Rabi' al-thani. Then, the most amazing thing will happen between (the months of) Jumada and Rajab. Then, a well-fed she-camel will be better than a fortress (castle) sheltering a thousand (people).[9]