Jahannam is the Islamic version of Hell, as such it differs from the depictions of the hoary netherworld seen in Christianity. It is known as "That which Breaks to Pieces", the "Blazing Fire" and "The Abyss". Jahannam was also mentioned in the Quran as the very opposite of Jannah which is the Islamic version of Heaven. The term comes from the Hebrew word Gehenna, originally the name of a valley outside Jerusalem.
Jahannam is described as having 7 gates, each for a specific group of sinners, the sinners have degrees (or ranks) based on their deeds and hypocrites are in the lowest of the depths of the Jahannam. Sinners are the fuel for the fire of Jahannam along with disbelieving Jinns and stones. The fire burns their skins, changing their colour to black due to its intensity. Jahannam has a shadow of smoke ascending in three columns, which yields no shade of coolness against the fierce blaze. Its sparks are described to be as "huge as a palace". Jahannam itself is described to have nineteen angels, who will punish wrongdoers. The leader of these angels, as stated in the Quran, is Maalik. According to Prophet Muhammad he is an angel, very severe and harsh, and he will listen to the request of dwellers of hell after 1000 years and that will also be in negative.
The food of Jahannam described in Hadith and the Quran includes a bitter thorn plant, Dhari, which does not nourish sinners, along with a tree named Zaqqum. Zaqqum is described in the Quran as a tree that springs out of the bottom of hellfire; the shoots of its fruit-stalks are like the "heads of devils" and eating it is similar to eating molten brass that will boil their insides "like scalding water". Sinners drink boiling water that will cut their bowels when they consume it. If they call for relief, they shall be given water described to be like molten brass, which will scald their faces. The residents of Jahannam wear garments of fire that will scorch them.
Various groups of people described to be in Jahannam include; disbelievers, hypocrites, polytheists, the People of the Book who reject the truth, arrogant rejectors of truth, sinners and criminals, tyrants, the unjust, transgressors, concealers of God's revelations, persecutors of believers, people who commit suicide and murders. Other people mentioned in Hadith include, but are not limited to; the arrogant, the proud and the haughty. Some prominent people mentioned in the Hadith and Quran are; Fir'awn, the wives of Nuh and Lut, Abu Lahab and his wife.
Some Muslim sects believe that unfaithful Muslims not true to their religion will be punished in Jahannam, other sects believe that Muslim souls are saved from its punishment. Most Sunni Muslims believe in the punishment of the unfaithful Muslims, but they also believe that they will eventually be forgiven. All Muslims believe that a disbeliever or non-Muslim who knew Islam and it's believers may remain there in Jahannam for eternity for not believing while they were living in the 'Dunia'; (literally means the lower one but it translates as the world, or the first life) — each person is judged according to their own circumstances. However, those who commit shirk will be condemned to the worst punishments in Jahannam for eternity. The Quran states that God may choose to make the punishment of hell temporary if He wills it according to His wisdom and knowledge.
The Quran and Hadith offer detailed descriptions of the methods of torture in Jahannam. The Quran states the punishments will be: the burning of skin, only to be replaced for reburning; garments of fire to be worn, and boiling water will scald the skin and internal organs; faces on fire; lips burnt off; backs on fire; roasting from side to side; faces dragged along fire; bound in yokes then dragged through boiling water and fire. The Hadith introduces punishments, reasons and revelations not mentioned in the Quran, the least-suffering person in Jahannam will have his/her brain boiling from standing on hot embers; and Hadith also relates that a person who committed suicide will be tortured on the Day of Judgment by the very means he/she used to end his/her life, as well as in Jahannam.
Jahannam in other Arabic literature
The word Jahannam also appears in secular texts and colloquial expressions, and in Arab-Christian writings. However it is used to refer to Hell and not specifically the Islamic concept of "Jahannam".