Many people have a distinct idea of what hell is, and many others are unsure and wonder about it's true nature.
The origins of the word "hell" can be traced back to a proto-germanic word 'halja' which means "one who covers up or hides something". Other potential origins for the word include places where the dead reside but do not necessarily describe punishments, and the environment is often misty or obscurative rather than fiery.
It is often described by later peoples (including Dante) as having sections, chambers, circles, or levels. In Mayan mythology, Xibalba is a nine-leveled underworld. In Greek Mythology, Hades involved punishment for some but was an all encompassing underworld, for the good and the bad, with Tartarus being the pit of punishment for those who were evil.
In the old testament, there is talk of Sheol being the underworld. Souls of the dead go to Sheol regardless of their deeds in life and are obscured from the light of God. There are punishments in Sheol as well, but they are not for everyone. Other interperetations of the old testament concur that Sheol is a subterranean place where shadows of our former selves exist in nothingness, with no real recollection of who or what they were.
A quote from Proverbs (30:16) describes Sheol as never satisfied. Jonah seems to refer to the whale as Sheol. Psalm 6 says that when in Sheol, souls cannot remember God.
In the new testament, Sheol is regarded as a place where souls go to wait for resurrection (reincarnation) and Gehenna is a place of eternal punishment.
In Ancient Egypt, a person's heart was weighed and they would go either to the Two Fields or be thrown to a devourer, to be prevented from eternal life.
In Judaism, Gehanna is described as a sort of purgatory or waiting room, souls inhabit this place temporarily and while they are there they become aware of the shortcomings of their life and/or are judged. In general it is accepted that souls will be in this place no longer than 12 months, after which the soul can ascend or be reborn, or both in parts. Gehanna is also viewed as a place of the present, not the future, and that simply the knowledge of being misaligned with God's will is punishment enough.
In Buddhism, six realms of rebirth are described, subdivided into varying degrees of pain or pleasure. One of the six realms is the Naraka, the lowest realm of rebirth and essentially, hell. One can be there for eons, however it is not permanent and the soul can be reborn into the other five realms to continue on its journey towards Nirvana.
In all the descriptions of hell I have found, each seems to symbolize the same idea:
If you do not do well/expand/evolve in this life, you will be made aware of the difficulties you had and you will be reborn to another life. It is possible that the next life will be one of great difficulty in order to teach you great lessons and help you to "catch up" and evolve faster, if you chose to listen to the lessons of that life as they occur.
Continuing on the path of divergence from God's will causes one to again be reborn in lives of challenge and darkness, which continues until the soul finally has had enough and reaches for the true light.
As we incarnate into different lives, our souls evolve and we come closer to the kingdom of God - aka Nirvana - aka paradise - aka heaven.
Jesus said many times that the kingdom of God is within us, implying that the deepest part of our beings is where the seed of the kingdom lives, and by implication that what is outside or without us is Sheol or hell.
The description of hel by Norse Pagans refers to it as a misty place, punishment is not mentioned, and it is ruled over by a being of the same name (as is also the case with Hades). The idea of mist brings to mind also the idea of the veil - and this ties into the concept of Sheol being a place where one cannot see the light of God any longer.
In this, hell again sounds like it is our physical body and mind - the mist or veil which obscures us from God and tricks us into thinking that we are of the Earth when in reality, we are of God.
Simply put, being incarnate is the equivalent of the levels of hell. By waking up to our surroundings and becoming aware of that seed of God within us, we can slowly pull ourselves up out of this mortal life and realm of confusion and bring ourselves back to God. The illusions of this life are the true flames of the fire, and it is only forever if we refuse to believe that we are the stuff of God and are divine, worthy of redemption, ressurection and reclaimation by God.