Hell is the abode which Allah (swt) has prepared for those who do not believe in Him (swt), those who rebel against His (swt) laws and disbelieve in His Messengers. It is the punishment for His (swt) enemies, the prison for evildoers.
It is the ultimate humiliation and loss; there is nothing worse:
"Our Lord! Verily, whom You admit to the Fire, indeed, You have disgraced him, and never will the Dhaalimoon [polytheists and wrongdoers] find any helpers" (3:192)
"Know they not that whoever opposes and shows hostility to Allah and His Messenger, certainly for him will be the fire of Hell to abide therein? That is extreme disgrace". (9:63)
"The losers are those who will lose themselves and their families on the Day of Resurrection. Verily, that will be a manifest loss!" (39:15)
How could Hell be other than we have described, when it is full of utterly indescribable torment, pain and grief? It is eternal and its inhabitants will remain there forever. Allah (swt) has condemned them and their place in the Fire:
"Evil indeed it [Hell] is as an abode and as a place to dwell" (25:66)
"This is so! And for the Tagheen [transgressors] - will be an evil final return - Hell! Where they will burn, and worst [indeed] is that place to rest!" (38:55-6)
The Keepers of Hell
Standing over Hell are MIGHTY and STERN angels who never disobey Allah subhaanahu wa ta'ala Who has created them. They do whatever He commands them, as Allah subhaanahu wa ta'ala says:
"O you who believe! Save yourselves and your families from a Fire whose fuel is men and stones, over which are [appointed] angels stern [and] severe, who flinch not [from executing] the Commands they receive from Allah, but do [precisely what] they are commanded." (66:6)
Their number is nineteen as Allah (swt) says:
"Soon I will cast him into Hellfire. And what will explain to you what Hellfire is? Naught does it permit to endure, and naught does it leave alone! Darkening and changing the colour of man! Over it are nineteen [angels as guardians and keepers of Hell]" (74:26-30)
This number was a challenge to the kuffaar who thought that they would easily overcome such a small number, but they did not realise that one of these angels has the strength to confront the whole of mankind on his own. For this reason, Allah (swt) said in the next aayah:
"And We have set none but angels as guardians of the Fire, and We have fixed their numbers  only as a trial for the disbelievers.." (74:31)
Ibn Rajab said, "What is known and well-established among the earlier and later generations (as-Salaf wal-Khalaf) is that the trial came about when the number of angels was mentioned and the kuffaar thought that it was possible to kill them. They thought that they would be able to fight and resist them. They did not know that humankind in its entireity would not be able to resist even ONE of them." (at-Takhweef min an-Naar, p.174)
These angels are the ones whom Allah subhaanahu wa ta'ala called the guardians of Hell:
"Those in the Fire will say to the keepers [angels] of Hell: "Call upon your Rabb to lighten for us the torment for a day!" (40:49)
The Location of Hell
The scholars differ as to where Hell is located at present. Some say that it is in the lower earth, other say that it is in the heavens, and yet others refrain from discussing the matter at all. This last group is correct, because there are no sound and clear reports that define the location of Hell. One of those who prefer not to discuss the matter at all is al-Haafidh as-Suyuti who said, "Do not discuss Hell, i.e. do not discuss where it is located, for none knows this except Allah (swt) and I know of no hadeeth that I could rely on with regard to this issue". (Siddiq Hasan Khan, Yaqazah uli al-I'tibar, p.47)
Sheikh Waliullaah ad-Dahlawee says in, his 'Aqeedah, "There is no clear text which states their location (of Paradise and Hell). They are wherever Allah (swt) wishes them to be, and we cannot comprehend all the universes created by Allah (swt)" (ibid, p.47). Siddeeq Hasan Khan says, commenting on these words, "I say, that is the best and most cautious of opinions, inshaa'Allah" (ibid).
The Vast Extent of Hell
Hell is huge and vast and immensely deep, as is proven by several things:
(1) Those who will enter Hell are innumerable, yet one of them will be so huge that his molars will be as big as Mount Uhud, and the distance between his shoulders will be equivalent to three days walking. Nevertheless, Hell will accommodate the huge number of Kuffaar and evildoers who have existed throughout history, in spite of their huge size, and there will still be room for more, as Allah says in the Qur'an:
"On the Day when We will say to Hell: "Are you filled?" It will say: "Are there any more to come?" (50:30)
The Fire of Hell is like a mill to which are brought thousands upon thousands of tons of grain, which it grinds tirelessly until it is all done, then waits for more. In the hadith that describes the debate between Paradise and Hell, it says that Allah (swt) said to Hell, "You are My Punishment; I will punish in you whomsoever I will". Both Paradise and Hell will be filled, but Hell will not be filled until Allah (swt) places His foot in it and it will say, "Enough, enough!". Then it will be filled and its different parts will come closer to one another. Allah (swt) will not wrong any one of His Creation. Reported by al-Bukhaari and Muslim from Abu Hurayrah (ra) (Jaami' al-Usool, 10/544). [See the narration from Anas in al-Bukhaari, Muslim and Mishkaat ul-Masaabeeh, 3/109 with a similar meaning].
(2) Another indication of its vast depth is the fact that a stone thrown from the top of Hell takes a very long time to reach the bottom. Muslim reports that Abu Hurayrah (ra) said:
"We were with the Messenger of Allah (saw) and we heard the sound of something falling. The Prophet (saw) said, "Do you know what that was?" We said, "Allah and His Messenger know best". He said, "That was a stone that was thrown into Hell seventy years ago and it was falling through Hell until now". (Muslim, Kitaab al-Jannah, Baab fi shiddat haar an-naar, 4/2184 no. 2844)
Haakim reports from Abu Hurayrah, and Tabaraani from Mu'aadh and Abu Umamah (ra) that the Prophet (Saw) said, "If there was a huge stone as big as seven khalifaat stones, and it was thrown from the edge of Hell it would fly through it for seventy years before it reached the bottom". (Saheeh al-Jaami' as-Sagheer, 5/58, no. 5124, Its isnaad is saheeh).
(3) The great number of angels who will bring Hell forth on the Day of Resurrection.
The Messenger (saw) described how Hell will be brought forth on the Day of Resurrection, concerning which Allah (swt) said,
"And Hell will be brought near that Day". (89:23)
The Prophet (saw) said,
"Hell will be brought forth that Day by means of seventy thousand ropes, each of which will be held by seventy thousand angels." (reported by Muslim from 'Abdullaah ibn Mas'ud, 4/2184 no.2842)
We can only image the vastness of this terrifying creation that requires such a huge number of strong and powerful angels whose strength is known only to Allah!
(4) Another indication of the vastness of Hell is the fact that two great creations like the sun and moon will be two rolled-up bulls in Hell. at-Tahhaawee reports, in Mishkil al-Aathaar, that Salamah ibn 'Abdur-Rahman said, "Abu Hurayrah told us that the Prophet (saw) said:
"The sun and moon will be two rolled-up bulls in Hell on the Day of Resurrection" al-Bayhaqi also reported this in "al-Ba'th wal-Nushur", as did al-Bazzaar, al-Isma'ili and al-Khattaabi, with an isnaad that is saheeh according to the conditions of al-Bukhaari, who reported in al-Saheeh al-Mukhtasar, with the wording "The sun and moon will be rolled up in Hell of the day of Resurrection". (Sheikh Naasir ud-Deen al-Albaani narrated this hadeeth in Silsilah al-ahadeeth as-Saheehah, 1/32, hadith no:124)
The Levels of Hell
There are variations in the degrees of heat in Hell, and in the levels of punishment which Allah (swt) has prepared for its inhabitants; there is not just one level.
As Allah says:
"Verily the hypocrites will be in the lowest depths [grade] of the Fire" (4:145)
It is said that both Paradise and Hell have different levels; the lower the level in Hell, the greater the intensity of the heat. The hypocrites will suffer the worst punishment, and so they will be in the lowest level of Hell.
Allah (swt) refers to the levels of Paradise and Hell in the Qur'an:
"For all there will be degrees [or ranks] according to what they did" (6:132)
"Is then one who follows [seeks] the good pleasure of Allah like the one who draws on himself the Wrath of Allah? His abode is Hell - and worst, indeed, is that destination! They are in varying grades with Allah, and Allah is All-Seer of what they do". (3:162-3)
'Abdur-Rahmaan ibn Zayd ibn Aslam said, "The levels of paradise go up and the levels of Hell go down" [Ibn Rajab, at-Takhweef min an-Naar, p.5]. It was reported from some of the Salaf that the sinners amongst the monotheists who enter Hell would be in the first level, the Jews would be in the second level, the Christians in the third level, the Sabians in the fourth level, the Magians in the fifth level, the polytheist Arabs in the sixth level and the hypocrites in the seventh level (1) Some books give names to these levels: the first is called Jahanam, the second Ladhaa, the third al-Hutamah, the fourth as-Sa'eer, the fifth Saqar, the sixth al-Jaheem, and the seventh al-Hawiyah.
There is no proof for this division of the inhabitants of Hell or the names that have been attributed to the various levels. The truth is that all of these names - Jahanam, Ladhaa, al-Hutamah, etc - are alternative names by which Hell in its entirety is known, and they are not applied to one part or another of it. It is also known that people will be placed in different levels of Hell according to the extent of their kufr and sins.
The Gates of Hell
Allah has told us that Hell has seven gates, as He (swt) said:
"And surely, Hell is the promised place for them all. It [Hell] has seven gates, for each of these gates is a [special] class [of sinners] assigned". (15:43-44)
Ibn Katheer commenting on this aayah, said: "This means that each gate has been allotted its share of the followers of Iblees who will enter it, and the will not be able to avoid it. May Allah (swt) protect us from it. Each will enter a gate according to his deeds, and will be assigned to a level of Hell according to his deeds."
It was reported from 'Ali ibn Abi Taalib (ra) that he said, during a khutbah (sermon): "The gates of Hell are such and-such". Abu Harun said, "They are in layers, one above the other". It is reported that he also said, "The gates of Hell number seven, one above the other. The first will be filled, then the second, then the third, until all of them are filled." (Tafseer Ibn Katheer, 4/162)
When the disbelievers come to Hell, its gates will be opened, and they will enter it, to remain there forever:
"And those who disbelieved will be driven to Hell in groups, till, when they reach it, the gates thereof will be opened [suddenly like a prison at the arrival of the prisoners]. And its keepers will say, "Did not the Messengers come to you from yourselves - reciting to you the Verses of your Rabb, and warning you of the Meeting of this Day of yours". They will say, "Yes" but the Word of torment has been justified against the disbelievers". (39:71)
After they are admitted, they will be told:
"Enter you the gates of Hell, to abide therein. And [indeed] what an evil abode of the arrogant!" (39:72)
These gates will be shut upon the evildoers, and they will have no hope of ever escaping from them after that, as Allah (swt) says, "But those who reject Our Signs, they are the [unhappy] Companions of the Left Hand. On them will be Fire vaulted over [all round]." (90:19-20)
Ibn 'Abbaas said, "vaulted" (literally: "shut over them") means that the gates will be locked". al-Mujaahid pointed out that the word used (mu'sadah) is the word used in the dialect of Quraysh to mean "locked" or shut" (Tafseer Ibn Katheer 7/298)
In the Qur'an Allah (swt) says:
"Woe to every [kind of] scandalmonger and backbiter, who piles up wealth and lays it by. Thinking that his wealth would make him last forever! By no means! He will be sure to be thrown into that which Breaks to Pieces. And what will explain to you that which breaks to pieces? The Fire of [the wrath of] Allah, kindled [to a blaze], which mounts [right] to the heart. It shall be made into a vault over them, in columns outstretched." (104:1-9)
Allah (swt) states that the gates of Hell will be locked behind them. Ibn Abbaas said, "In columns outstretched" means that the gates will be stretched out". 'Atiyah said, "It is a pillar of iron". Muqaatil said, "The gates will be closed firmly behind them and locked with a bolt of iron, so that the pain and heat will be intensified. The expression "stretched forth" applies to the "pillar", meaning that the bolts with which the gates are locked will be very long, because a long bolt is stronger than a short one" (Ibn Rajab, at-Takhweef min an-Naar, p.61)
The gates of Hell may be opened and closed before the Day of Judgement. The Prophet (Saw) told us that the gates of Hell are locked during the month of Ramadhan. at-Tirmidhi reported that Abu Hurayrah said the Prophet (saw) said: "When the first night of Ramadhan comes, the Shayaateen and evil jinns are chained up. The gates of Hell are closed and not one of them is opened. The gates of Paradise are opened and not one of them is closed." (Ibid, p.66)