Hell, a most interesting word. Germanic, of course, and a shorthand for various Persian, Semitic, and Greek concepts that involve an absence of the presence of both light and God.
In the ancient writings we quaintly term the "Old Testament," in the earliest writings purported we find not a concept of eternal punishment, rather a physical loss of blessing. Later in these same books we find imagry that suggest a place of separation from God, a place,not necessarily of eternal punishment, rather a dark place, "Outer Darkness," "Sheol," etc., more akin to the Hellenic concept of Hadess than an eternal toruture chamber.
Finally, after contact with the Persians, we find the Zoroastarian concept of the physical abandonment of God to the evil for a spiritual place, the concept of a final judgment is relized.
Then in the time of Our Lord, we find such a place for the dead termed "Gehenna," a garbage dump outside the city walls of Jerusalem, "pit," etc., where there shall be "wailing and the gnashing of teeth." Finally, in the visions of John of Patmos, we see something upon many have latched: a Dantesque Concentric Circles of Torment, minus only harpies and flying monkeys.
Now, one would imagine that those who tout the Johannine vision as literal would also have the common sense to have read the first part of the letter: John addresses it to seven churches in Asis. He is in a visionary state and Our Lord's voice tells him to take up a pen and write. He does and he starts to see a series of physical things: seven candlesticks and seven stars. Next, confused, Our Lord clarifies what he has seen, the seven candlesticks are the seven churches of Asia to whom John is to write. The seven stars represent the angels who guard each church.
Following this interpretation, Our Lord no longer directly addresses John, and the visions get progressively more odd and convoluted. He sees 144,000 elders, the City of God, streets of gold, and its opposite: the ultimate showdown between Our Lord and Satan. There are demons, seven-headed beasts with ten crowns, a woman clothed with the sun and crowned with stars, etc.
There is little else after this to mention until the imagry is adopted by the Medieval Church and used in its iconography. Then Dante in Florence abandons Vulgar Latin for Modern Tuscan and writes the Divine Comedy. This is about it until the rise of the "Darbyites" who invent rapture and tribulation in the early 19th Century. All calms down until Isaac Scofield publishes his reference Bible and still largely ignored, is rediscovered and grown to be beloved by various odd, heterodox sects, and even largely adopted by the ci divant sane sober Souther Baptist Convention's minister and given the unofficial nihil obstat.
What is hell? Who says what hell is? Many Orthodox Jews deny hell's existence, they claim that it is eternal loss of the soul: the soul dies. Their names are not written in the Book of Life and the are not resurrected.
Hellfire: scaring people into giving to their sacerdotal betters since at least 500 B.C.
It would be the absolute height of hubris, in my opinion, to dare presume how and when and where the Almighty whose property is always to show mercy might condemn the largest portion of dead mankind to an eternal dinner party of nasty food, punctuated with fingernails being pulled out, and Karl Marx having written a lot of new books that he decides to read aloud on the concept of worker alienation while John Hagee shows an eternal slide show as Sanjaya offers his "vocal stylings, a side and very loud argument simultaneously taking place between Lady Jane Grey and Mary I Tudor.