Arabic term meaning guided one. He is an Islamic savior who will change Islamic societies into perfection before the day of resurrection. In a disputed Hadith, Mohammud purportedly stated, "Even if the entire duration of the world's existence has already been exhausted and only one day is left before the Day of Judgment, Allah will expand that day to such a length of time, as to accommodate the kingdom of a person out of my Ahl al-Bayt (my descendants) who will be called by my name. He will then fill the Earth with peace and justice as it will have been filled with injustice and tyranny before then." Sahih Tirmidhi, V2, P86, V9, P74-75.

Both Sunni and Shia sects have their own perspective about Mahdi. The majority of Sunni approach this subject with doubt, on the other hand, the majority of Shiites believe in this prophecy. The only available support comes from weak Hadith, and the Quran remains silent on this prophecy.

Sunni and Shiite agree that he is a descendent of Muhammad through Mohammed's daughter, Fatima. He was born in Medina. Shiites goes further by claiming that he was born in 868 and is still alive due to going into occultation at the age of 5. His father, Hasan Al-Askari, was the 11th Shiite imam. Narjas, a Byzantine princes was his mother. Shiite know him as the awaited Mahdi, the 12th Imam.

The 6th Shiite imam, Jafar Al-Sadiq (702 –765), purportedly stated, "Before the appearance of the one who will rise, peace be upon him, the people will be reprimanded for their acts of disobedience by a fire that will appear in the sky and a redness that will cover the sky. It will swallow up Baghdad, and will swallow up Kufa. Their blood will be shed and houses destroyed. Death will occur amid their people and a fear will come over the people of Iraq from which they shall have no rest."



References:

http://al-islam.org/al-tawhid/default.asp?url=mahdi/discussion.htm
http://www.promisedmehdi.com/