In Buddhism, the idea is quite simple. We see that in this life people are born in many different circumstances. Some suffer a lot. And animals also - some of those also suffer a lot. And our bodies are very vulnerable to being harmed. Then also have the idea that there are many different forms of life not known to us directly. In terms of modern science these might be lifeforms on other worlds. But they might also be lifeforms that have lives with different laws of physics.

Traditionally Buddhism began in India with the background belief that there are many other forms of life with bodies made of light for instance. And also realms of pure thought, where you may just experience peace, or bliss, no body, no world around you, just a mental state, for billions of years.

So if you have the idea that there could be as much variety in forms of life as that - it's also possible to have realms where the beings there are capable of experiencing suffering not just like humans, but more than we can even imagine. Humans can't stand much pain - extreme levels for us - screaming etc - but if you experience too much pain you just faint.

So the hell realms in Buddhism are like that. Extension of ordinary suffering we are aware of into extreme states of suffering that may last for billions of years, just as in the other direction there may be forms of life that experience nothing but bliss for billions of years.

But none of these are permanent. Eventually the blissed out being in a state of pure thought exhausts whatever conditions lead to that situation and will be reborn again with an ordinary body like us, ordinary suffering and pleasures. The hell being also will eventually exhaust the conditions that lead to their billions of years of suffering and be reborn as a being like us too.

And life as a human is thought to be the most precious of all. When you are blissed out,  is very hard to even think about impermanence, or to pay much attention to it if you know about it. Something that will happen a billion years into the future, with nothing but bliss until then - even if you know it - would you do anything about it?

And when you are in extreme suffering, then it's hard to think about anything except your suffering.

As humans we have a balance of both. So - of course variation also, if you live in very fortunate conditions you may be a bit like the long lived blissed out beings, for us even a few decades of happy conditions is enough to make it easy to forget about impermanence. And if you suffer a lot, then is hard to think about anything except your suffering and problems. But for most of us, there's some suffering, and some unsatisfactoriness, but yet enough stability and happiness to reflect on our situation and do something about things, try to find a path, realize we need to be a bit more aware of others, see that we need to work on ourselves, that there are things we need to do.

What we don't have in Buddhism is any idea at all that any of this is a punishment, caused by some external deity. Nor is the Buddhist idea of karma based on the idea of a kind of tit for tat. As Tai Situ said once in a talk, it doesn't mean that if a mosquito bites me on the nose, that I must have bitten it on its nose in the past :).

As an example given by the notable Thai Therevadhan scholar Prayudh Payutto, if you climb a flight of stairs - that's karma. When you get to the top, then you can no longer touch the ground, you may be tired after the climb, etc. You may get a great view. You may then be able to talk to your friend. So there are many effects of our actions, in this case of climbing a flight of stairs, some positive, some negative, many neutral. But it's not because someone punished you for climbing the stairs by making you tired, or rewarded you with a good view. It's just because those are consequences of climbing a flight of stairs.

That's how Buddhists think about karma - action and consequences. Extending that to past and future lives, it's the same idea. No idea of punishment or reward in the slightest. Many people get this wrong when they talk about Buddhism so it's worth emphasizing this a few times.

The origin of all this suffering, Buddha taught, is fundamentally ignorance and confusion. Of course there are many more immediate causes, e.g. someone who gets angry and kills someone and then most likely regrets it immediately - the anger is the immediate cause of their suffering. And there are many long term consequences also of what they did. And having fragile bodies makes us vulnerable to accidents and the violence also of others.

But the fundamental cause, he taught, behind all that, is that it's because we try to treat the world as permanent when it's impermanent, and don't properly see our own nature either, that we suffer so much, and behave so unskillfully. And on top of that many other confusions also arise. In the Mahayana traditions they take this so far as to say that even space and time as we understand it are also confusions - a way of straightjacketing a reality that is far more fluid than we realize.

And it's difficult to deal with them because when you become aware of some of those confusions there's a tendency to try to forcefully stamp them out - but that is even worse, makes you more confused than you were before. Because the idea to try to do that is rooted itself in a confused view of who and what we are. It's based on the confused idea that in some way by removing those confusions we've identified we can established something permanent in the world where we can be at peace with ourselves and the world. But that's itself a confused idea and the truth Buddha taught is much more fluid than that.

The way forward has to come from something other than our ordinary self as we normally think of ourselves - that's far too confining and claustrophobic a way of looking at the world to be a basis for solving the problem of suffering. Anything we try just makes things worse.

We may begin to have a glimpse of a way forward at timese when we realize that and give up on attempts to stamp out our own confusions. But then the confusions just come in again in more subtle ways, e.g. if you start to think that glimpsing a way forward makes you a better person, in some ways has solved your problem if just a bit - that's  just the same old confusion in another form and you've got nowhere, except perhaps some inkling that there is a way forward though you can't find it yet. Still - that's the path of the Buddha, he taught that it is possible to find your way through all that, that at some point, all these confusions can just drop away - that when you really really see what is going on, not just build up fantasies about it, you will drop it all instantly, like letting go of a hot coal you find you've been holding in your hand all this time.

And the main reason for reflecting on the Hell Realms in Buddhism is to draw attention to the value of our present life, that we aren't suffering so much that it is impossible to think clearly. And that we have this wonderful opportunity to do something positive about our situation.

Buddhist teachers often don't talk much about Hell Realms to Westerners - because it's easily misunderstood - and so may not help relate to life in a positive way as it does traditionally, thinking how positive and wonderful this life is.

Also of course we have no direct evidence of either the hell realms or the realms of pure pleasure or even more subtle states beyond distinctions of pain and pleasure that they talk about in the teachings. And it's not a creed, so you don't have to believe in them to be a Buddhist.

It's just extrapolation, but I think whatever you think about them - if we do have multiple past and future lives, surely we must sometimes take birth in bodies that are more prone to suffering than the ones we are in now, and at other times take birth in conditions of great pleasure and happiness for our entire life. That much seems obvious.

The idea of a hell realm in Buddhism is an extension of that - suggesting the extremes are greater than we realize from just looking at the animals and humans in the world we know of. And as far as I know all the traditional Buddhist traditions talk about hell realms - though in some such as Zen Buddhism they will say very little about it, as the focus is so much on meditation and relating to what we can see for ourselves in this life.

See also my occasional blog about Buddhist ideas where I talk about some of the misconceptions of Buddhist ideas of Karma by many Westerners Some ideas about Buddhist teachings