My answer is more about what they are not, because I’ve come across widespread confusion when talking about them to other Westerners, and I think you can’t really understand what they are about until you clear up these misconceptions, which you might not realize you have. The truths themselves are simple to state, not many words. You may feel they surely have to be easy to understand. However, after Buddha gave the teachings to his four companions in the wheel turning sutra, only one of them, Koṇḍañña , saw the true meaning of the teachings

“This is what the Blessed One said. Elated, the bhikkhus of the group of five delighted in the Blessed One's statement. And while this explanation was being spoken, there arose in the venerable Koṇḍañña the dust-free, stainless vision of the Basic Pattern: "whatever is patterned with an origination, all that is patterned with a cessation."”
the Four True Realities for the Spiritually Ennobled Ones

So if you find yourself a bit puzzled about them, not sure what they mean, that’s good. Let yourself experience that confusion :). It is a sign of wisdom actually, to feel you don’t fully understand what they mean. That’s the start of the Buddhist path it’s not that you realize the four truths, or you’d be enlightened already. It is that you find them intriguing and feel there is some truth in them that you want to follow up.

But before one can get to that point, we do need to clear up the misconceptions! Otherwise you have no chance.

First of these misconceptions is the idea that the aim of a Buddhist following the four truths is to end rebirth. It’s true that all the sutras (collection of texts recording the teachings of the Buddha) say that after he become enlightened, Buddha never took rebirth again, that it's his last rebirth. Everyone agrees, that's his paranirvana. But it doesn't follow at all from that, that when he became enlightened as a young man, his main aim was to end rebirth, or that that should be the aim of the practitioner.

Cessation in the sense of the four truths is the cessation of the suffering of birth, old age, sickness, death, and all forms of unsatisfactoriness. This, Buddha himself said, he realized when he became enlightened. Buddha reached cessation, nirvana, as a young man under the Boddhi tree. Not when he died.

And yet, he still got old, and experienced sickness, and died after he became enlightened. That’s something you need to contemplate when you try to understand what he meant by cessation here. How can you reach cessation of suffering, and at the same time continue to live in this world, teach others, get sick, die? What does it mean? That’s one of the central points to contemplate as a Buddhist. It’s like a Zen koan.

CESSATION IS NOT A KIND OF FROZEN IMMOBILITY

Another confusion is the idea that Buddha reached nirvana by ending karma and achieving a kind of state of doing nothing, immobility.

Normally the third and fourth truths are stated like this (with small variations)

3. The truth of the cessation of dukkha (suffering, anxiety, unsatisfactoriness)

4. The truth of the path leading to the cessation of dukkha

That’s from the old version of the wikipedia article on the Four Noble Truths

This is the statement of the third truth in the current version of this article. It differs from all other statements of the third truth that you will find (including indeed the other answers to this question) by stating it as a path to end rebirth.

3. “Nirodha, the cessation of dukkha. By stopping this craving and clinging nirvana is attained, no more karma is produced, and rebirth and dissatisfaction will no longer arise again”

The fourth truth is stated similarly “By following the Noble Eightfold Path, …, craving and clinging will be stopped, and rebirth and dissatisfaction are ended”

I can’t stress enough how very wrong this idea is. It suggests Nirvana as an effect you try to create, as some kind of heaven state. Perhaps it is a melding of views of other religions with Buddhism. It suggests that the idea is to stop karma in order to reach a “karma free state”. This is not based on any Buddhist scholar source but is a restatement of the third and fourth truths by a wikipedia editor, made by smashing together cites on nirvana and paranirvana. It embodies most of the Western misunderstandings about the four truths.

If that was what Buddha meant to say, why did he always teach the four noble truths as a path to cessation of suffering? Why didn’t he teach it as a path to end karma and to stop rebirth if that was what he really meant?

In Buddhist teaching we have countless karmic effects from previous life. How could you “stop producing karma”? Anything you do, even if you were to sit immobile in meditation for the rest of your life, that still has effects. You still breathe, people would stop and wonder why you were staying still, you would get hungry and need to eat, need to drink, get old. In Buddhist teachings on karma, positive, negative and neutral karma all binds you to samsara. They don’t “balance each other out”. After Buddha reaches enlightenment, he is still able to interact with the world and other humans and creatures to teach them.

So whatever it might mean to become enlightened and to no longer be caught up in samsara, it doesn’t mean that you have to stop all interactions and stop doing anything that has an effect. That’s not why Buddha entered paranirvana when he died, whatever paranirvana means, it can’t mean this.

According to Buddha’s teachings that couldn’t work anyway. Nirvana would be a conditioned produced thing, dependent on conditions, ending when whatever is maintaining it ceases. If it is due to stopping doing anything that has an effect and so stopping rebirth, by a kind of immobility basically - what happens if after a few trillion or quadrillion years there is some movement in your endless immobility and you are no longer able to stop rebirth any more?

Rebirth is not mentioned anywhere in the Pali text for the wheel turning sutra itself, where the four truths are first presented. The canon itself is vast, a whole encyclopedia of books and most Buddhists never read it in its entirety, just because there is too much to read. You might wonder if perhaps somewhere else he gives different teachings on this.

However Buddhist scholars expert on the Pali canon who have read it in its entirety are clear about it, that nirvana, cessation, is something you can realize in this very life. There may be some sects that have other views but this is the central teaching of the main branches of Buddhism.

TRUTH IS, NIRVANA IS

Walpola Rahula puts it clearly (this is perhaps the most highly regarded of all books on Therevadhan Buddhism in English)

"It is incorrect to think that Nirvāṇa is the natural result of the extinction of craving. Nirvāṇa is not the result of anything. If it would be a result, then it would be an effect produced by a cause. It would be saṃkhata ‘produced’ and ‘conditioned’. Nirvāṇa is neither cause nor effect. It is beyond cause and effect. Truth is not a result nor an effect. It is not produced like a mystic, spiritual, mental state, such as dhyāna or samādhi. TRUTH IS. NIRVĀṆA IS. The only thing you can do is to see it, to realize it. There is a path leading to the realization of Nirvāṇa. But Nirvāṇa is not the result of this path. You may get to the mountain along a path, but the mountain is not the result, not an effect of the path. You may see a light, but the light not the result of your eyesight.

...
In almost all religions the summum bonum can be attained only after death. But Nirvāṇa can be realized in this very life; it is not necessary to wait till you die to ‘attain’ it."

(from The Third Noble Truth - Walpola Rahula: What the Buddha Taught)

PATH OF SEEING THINGS FOR YOURSELF

There is another major problem with this idea that the aim of Buddhists is to end rebirth.

If he had taught in this way, it would require practitioners to believe in rebirth before we can become a Buddhist. But Buddha taught that we need to see things for ourselves:

“'Don't go by reports, by legends, by traditions, by scripture, by logical conjecture, by inference, by analogies, by agreement through pondering views, by probability, or by the thought, "This contemplative is our teacher."

When you know for yourselves that, "These qualities are unskillful; these qualities are blameworthy; these qualities are criticized by the wise; these qualities, when adopted & carried out, lead to harm & to suffering" — then you should abandon them.' Thus was it said. And in reference to this was it said.

"… When you know for yourselves that, 'These qualities are skillful; these qualities are blameless; these qualities are praised by the wise; these qualities, when adopted & carried out, lead to welfare & to happiness' — then you should enter & remain in them.”

Kalama Sutta: To the Kalamas

Now this is a much misunderstood passage. The translator notes :

“Although this discourse is often cited as the Buddha's carte blanche for following one's own sense of right and wrong, it actually says something much more rigorous than that. Traditions are not to be followed simply because they are traditions. Reports (such as historical accounts or news) are not to be followed simply because the source seems reliable. One's own preferences are not to be followed simply because they seem logical or resonate with one's feelings.

Instead, any view or belief must be tested by the results it yields when put into practice; and — to guard against the possibility of any bias or limitations in one's understanding of those results — they must further be checked against the experience of people who are wise. “

So, he isn’t saying - go ahead and believe anything you like just on a whim. It’s after observation and careful analysis and Buddha gave many specific and detailed teachings and other teachers also after him, through to the present day. Even in Zen. Though they have such a different way of teaching, there are Zen scholars, and it's a sutra tradition. Ordinary practitioners don't need to learn this at all to be a Buddhist but it is there for those that need it. Those of a scholarly bent will spend many years learning the detailed teachings.

Buddha is not saying here that you can just make up anything, spin it out of your own imagination, follow your own made up path, and call it Buddhism :). Westerners so often misinterpret it like that.

But on the other hand, Buddhists consider that there is no virtue at all in believing in these detailed teachings for their own sake either.

EXAMPLE OF SOMETHING WE CAN SEE FOR OURSELVES - THE TRUTH OF SUFFERING AND UNSATISFACTORINESS

For instance we can all see the truth of suffering and unsatisfactoriness. Also one can come to see for oneself that we have no permanent state of satisfaction and permanent worldly happiness in this life, everything is subject to change. That's the basic starting point of the Buddhist teachings, and it is something you come to see for yourself.

If you can imagine somehow someone had never experienced suffering and had no idea what pain or unsatisfactoriness was - there wouldn't be any value in them saying "I believe in suffering". But seeing it for yourself is of great benefit. Understanding that yourself and others suffer is a basis for compassion for others and for yourself too and that's the starting point of the path.

So all the teachings are understood in this sense. Things that you can come to see for yourself just as you see the truth of suffering and can come to see that you can’t establish a state of permanent worldly happiness in this life. That much as you may enjoy chocolate for instance, that you can’t keep yourself permanently happy by continually eating chocolate :). And one can come to see that there is nothing else either that can lead to permanent worldly happiness. Many things like that which we can see for ourselves.

REBIRTH AS SOMETHING MOST OF US CAN’T SEE FOR OURSELVES - AND NEED FOR AN OPEN MIND ABOUT IT

So if the central teaching, the Four Noble Truths were understood as a teaching about ending rebirth, then that would be a major block for most practitioners right at the get go, because most of us can’t even see that we are reborn from our own experience. In fact Buddha never mentions rebirth anywhere in this central wheel turning sutra. In many other places yes, but not in this central teaching at all.

Indeed not only are we not required to believe in rebirth - it’s also important to keep an open mind about it. I do believe that I have been reborn many times and will do so again in the future. But I don’t know that from my own experience and with Buddha’s teachings, if you follow his path, it is very very important to be clear about what you know for sure, such as the truth of suffering ,and what you believe but haven’t established, e.g in my case whether I am reborn. And to keep an open mind about the things one can’t see for oneself. So to make the aim to end rebirth would be to close the minds of practitioners about rebirth, as they would have to have specific ideas there that they have to believe without being able to see them for themselves before they could become a Buddhist and follow the path. This would make it hard to impossible for them to approach the subject of rebirth with an open mind, which is so important along the Buddhist path. That goes right against the central thrust of Buddhism.

SO AIM CAN’T BE TO END REBIRTH

So the aim can’t be to end rebirth and it isn’t. That’s just a Western misconception about Buddhism. It may be an aim in Hinduism, I’m not sure, but it can’t be in Buddhism. Not in the central sutra based traditions at least since the sutras are clear on this point.

Sometimes Buddhism may be taught in ways that seem to suggest that the aim is to acquire beliefs (such as rebirth), but it's not really and at some point it gets challenged. In some traditions of Tibetan Buddhism they build up whole elaborate systems of belief,only to demolish them and then build up another. The sand mandala and the way it gets washed away by the water at the end is to do with that.

There are many ways to teach. Some very elaborate, some very simple. In the Indian traditions the teachings given to the great Indian mahasiddhas were often very simple, just a few words. The same is also true of Zen Buddhism. They may not teach the four noble truths in so many words. But even Zen Buddhism does have the four noble truths as a central teaching. Even if for some practitioners they just need to look at a flower to see the truth, with no words at all.

GOOD SOURCES ON THE FOUR NOBLE TRUTHS

So that leads to the question, if the present version of the wikipedia article is not to be trusted, what are good sources on the Four Noble Truths?

Well, even the Western academics will say that the best sources, if you want to learn how contemporary Buddhists understand the sutras, are the Buddhist scholars themselves.

Buddhism has always been a religion with many scholars. Back in the sixth century through to 1200, the Buddhist Nalanda University was one of the centers of learning in the world with scholars coming to it from far and wide..

These are the remains of the library of Nalanda University - reported to have had hundreds of thousands of books, and reportedly burnt for three months when it was destroyed around 1200, after flourishing for around six centuries. (That's according to Persian historian Minhaj-i-Siraj - see History of Libraries entry on Nalanda)

And there is and was a fine scholarly tradition in all the main Buddhist countries, such as Sri Lanka, Thailand, Japan, Tibet etc.

The old version of the four noble truths article relied extensively on these Buddhist scholars. Four Noble Truths

Where the new version goes wrong I think, is that it relies over much on the Western academics, often obscure ones. Their articles are often dense and technical, and though many of them are excellent and there are some really good Western scholars, others sometimes contain misunderstandings, and even if accurate, they are so technical that they are often easy for readers who are not fully involved in the complex debates to misunderstand or to interpret as meaning almost anything.

So, if you accept that the Buddhist scholars are the best sources for understanding how Buddhists themselves understand the four truths, then which are the best ones to go for?

Well it’s a vast literature and I am not a scholar myself, not widely versed at all. But I can make a few suggestions to get started.

I think many would say that the best source on the Four Noble Truths in English is the book "What the Buddha Taught" by Walpola Rahula. He straddled both worlds as a one of the top Sri Lankan scholar monks, and also the first bikkhu to become a professor in an American university.

He writes very well, in plain English, but don’t let that mislead you. He is an expert on this, with a thorough understanding of the Pali Canon - the earliest teachings we have from the Buddha. These teachings are central to all the Buddhist sutra traditions - there are some variations but he touches on that also briefly. Here is the link again: "What the Buddha Taught"

For a Zen perspective, try The Four Noble Truths - International Zen Association United Kingdom

And for an idea of how they are understood in Tibetan Buddhism, you could read the Dalai Lama's talk about the four truths. He's not just the Dalai Lama, he's also a scholar monk too, completed his training as a young man, and astonished his peers with his erudite understanding of Tibetan Buddhism, so he is a good source for Tibetan Buddhism. So, at least for those who think that the best way to find out how Buddhists understand the sutras is to ask the scholar monks, then the Dalai Lama, as one of the top scholar monks in the Tibetan tradition, is one of the best to go to to find out about Tibetan Buddhism :). One of his talks on the subject is here: Lama Yeshe Wisdom Archives

Another good source in the Therevadhan path is this article by Venerable Sumedho from the Amaravati monastery in Southern England. I've heard him talk in Oxford. And we actually meditated in their place too, the Tibetan Buddhist group I belonged to in Oxford, when they had nowhere else to go.

Anyway they are authentic good Therevadhan monks that follow the traditional approach even setting out with begging bowls to beg for food every morning in the English countryside. And he's a good teacher. So, this gives an idea of how a Therevadhan teacher would teach the subject.

The Four Noble Truths

There are many other sources, but those should get you off to a decent start.

For an overview, and more cites to follow up, the previous version of the wikipedia article was good, with many quotes from Buddhist scholars: Four Noble Truths

The sutra where Buddha first taught the four truths, according to the sutras, is the Dhammacakkappavattana Sutta - the “wheel turning” sutra where Buddha set in motion the wheel of the teachings. There are several alternative translations of it here: the Four True Realities for the Spiritually Ennobled Ones

Oh, and though all the traditions agree that Buddha entered paranirvana so can never take rebirth again, the later Mahayana traditions especially say that other Buddhas don’t necessarily enter paranirvana when they die. They are able to continue to interact, even can “emanate” as new rebirths, young babies born like everyone else that somehow carry the inspiration of a Buddha from birth, whatever that means. Even can “emanate” as inanimate things like rivers, bridges, flowers, plants.

Well in a way the whole world carries the inspiration of the historical Buddha for a Buddhist following the path. I’ve heard it described by my main teacher for many years as his “impure land” because it was blessed by him taking birth here, though it is not a “pure land” where everything carries the inspiration of the teachings.

However, in the Mahayana teachings, there’s the idea that there’s some sense in which this inspiration can be more direct for emanations of Buddhas. I’m not sure how it works, so just mentioning it. This is a Mahayana idea, I don’t think you have it in Therevadhan Buddhism, the idea of an emanation of a Buddha??

See An Interivew with Dilgo Khyentse Rinpoche

STANDARD WARNING - PLEASE DON’T EDIT THE WIKIPEDIA ARTICLE TO TRY TO “FIX” THESE ISSUES

I encountered many of these misconceptions while attempting to get other editors to fix the Wikipedia article on the topic and while talking to others off wiki about it. If you want to read about that episode, see my answer to Is Wikipedia biased? I am currently reaching the end of a six month ban on mentioning the “four noble truths” anywhere in wikipedia just because of attempts to get them to fix it by talking on the talk page of the article.

Wikipedia has a strict policy on canvasing and proxy editing. It’s absolutely prohibited to recruit people to the articles to edit them in your favour once a dispute has arisen there (as in this case). You can understand why - otherwise whenever someone was opposed by another editor on the talk pages they would just get all their friends to open wikipedia accounts and shout loudly that they are right in the debate and win the day.

It’s absolutely fine to encourage friends and other editors to come and edit wikipedia before a dispute arises. But once it arises, then you run into this issue that recruiting anyone you know will support you in the debates counts as canvasing and is forbidden.

So - please don’t try to fix the article as a result of reading this. We just have to leave them to it and hope that some day it gets fixed in the natural course of events. Thanks!

This originates as Buddhist sources on the Four Noble Truths by Robert Walker on Some ideas about Buddhist teachings

For sources - see the sources for the original version of the Four Noble Truths article on Wikipedia before the rewrites. As you’ll see, it is heavily cited throughout.