The basis of Buddhism is a doctrine known as the Four Noble Truths. The First Truth is that all life is suffering, pain, and misery. The Second Truth is that this suffering is caused by selfish craving and personal desire. The Third Truth is that this selfish craving can be overcome. The Fourth Truth is that the way to overcome this misery is through the Eightfold Path.
The Four Noble Truths is a fundamental concept taught by the Buddha.
The truth of suffering (Dukkha)
The truth of the origin of suffering (Samudāya)
The truth of the cessation of suffering (Nirodha)
The truth of the path to the cessation of suffering (Magga)

The fourth Noble Truth, in which the Buddha set out the Eightfold Path, is the prescription, the way to achieve a release from suffering.

The First Noble Truth

Suffering(Dukkha) Suffering comes in many forms. Three obvious kinds of suffering correspond to the first three sights the Buddha saw on his first journey outside his palace: old age, sickness and death.
But according to the Buddha, the problem of suffering goes much deeper. Life is not ideal: it frequently fails to live up to our expectations.

Human beings are subject to desires and cravings, but even when we are able to satisfy these desires, the satisfaction is only temporary. Pleasure does not last; or if it does, it becomes monotonous.
Even when we are not suffering from outward causes like illness or bereavement, we are unfulfilled, unsatisfied. This is the truth of suffering.

Some people who encounter this teaching may find it pessimistic. Buddhists find it neither optimistic nor pessimistic, but realistic. Fortunately the Buddha’s teachings do not end with suffering; rather, they go on to tell us what we can do about it and how to end it.

The Second Noble Truth

Origin of suffering (Samudāya)
Our day-to-day troubles may seem to have easily identifiable causes: thirst, pain from an injury, sadness from the loss of a loved one. In the second of his Noble Truths, though, the Buddha claimed to have found the cause of all suffering – and it is much more deeply rooted than our immediate worries.
The Buddha taught that the root of all suffering is desire, tanhā. This comes in three forms, which he described as the Three Roots of Evil, or the Three Fires, or the Three Poisons.

The three roots of evil
These are the three ultimate causes of suffering:
Greed and desire, represented in art by a rooster
Ignorance or delusion, represented by a pig
Hatred and destructive urges, represented by a snake

The Fire Sermon
The Buddha taught more about suffering in the Fire Sermon, delivered to a thousand bhikkus (Buddhist monks).
Bhikkhus, all is burning. And what is the all that is burning?
The eye is burning, forms are burning, eye-consciousness is burning, eye-contact is burning, also whatever is felt as pleasant or painful or neither-painful-nor-pleasant that arises with eye-contact for its indispensable condition, that too is burning. Burning with what? Burning with the fire of lust, with the fire of hate, with the fire of delusion. I say it is burning with birth, aging and death, with sorrows, with lamentations, with pains, with griefs, with despairs.

The Third Noble Truth

Cessation of suffering (Nirodha)
The Buddha taught that the way to extinguish desire, which causes suffering, is to liberate oneself from attachment.
This is the third Noble Truth – the possibility of liberation.
The Buddha was a living example that this is possible in a human lifetime.

Bhikkhus, when a noble follower who has heard (the truth) sees thus, he finds estrangement in the eye, finds estrangement in forms, finds estrangement in eye-consciousness, finds estrangement in eye-contact, and whatever is felt as pleasant or painful or neither-painful- nor-pleasant that arises with eye-contact for its indispensable condition, in that too he finds estrangement.
“Estrangement” here means disenchantment: a Buddhist aims to know sense conditions clearly as they are without becoming enchanted or misled by them.

The Fourth Noble Truth

Path to the cessation of suffering (Magga)
In order to end suffering, you must follow the Eightfold Path. This liberation from suffering is what many people mean when they use the word “enlightenment.”
The path to the end of suffering is gradually seeking self-improvement through the eight elements. The path to the end of suffering can extend over many lifetimes, throughout which every individual rebirth is subject to karmic conditioning. Craving, ignorance and other effects will disappear gradually, as progress is made through each lifetime.
The eight divisions
The eight stages are not to be taken in order, but rather support and reinforce each other:
Right Understanding – Sammā ditthi
Accepting Buddhist teachings. (The Buddha never intended his followers to believe his teachings blindly, but to practise them and judge for themselves whether they were true.)

Right Intention – Sammā san̄kappa
A commitment to cultivate the right attitudes.
Right Speech – Sammā vācā
Speaking truthfully, avoiding slander, gossip and abusive speech.
Right Action – Sammā kammanta
Behaving peacefully and harmoniously; refraining from stealing, killing and overindulgence in sensual pleasure.
Right Livelihood – Sammā ājīva
Avoiding making a living in ways that cause harm, such as exploiting people or killing animals, or trading in intoxicants or weapons.
Right Effort – Sammā vāyāma
Cultivating positive states of mind; freeing oneself from evil and unwholesome states and preventing them arising in future.
Right Mindfulness – Sammā sati
Developing awareness of the body, sensations, feelings and states of mind.
Right Concentration – Sammā samādhi
Developing the mental focus necessary for this awareness.
The eight stages can be grouped into Wisdom (right understanding and intention), Ethical Conduct (right speech, action and livelihood) and Meditation (right effort, mindfulness and concentration).
The Buddha described the Eightfold Path as a means to enlightenment, like a raft for crossing a river. Once one has reached the opposite shore, one no longer needs the raft and can leave it behind.

Summary
The Four Noble Truths is the basis of Buddhism. The First Truth is that all life is suffering, pain, and misery. The Second Truth is that this suffering is caused by selfish craving and personal desire. The Third Truth is that this selfish craving can be overcome. The Fourth Truth is that the way to overcome this misery is through the Eightfold Path.