Here's another good excerpt from the same wikipedia article on Buddhism (en.wikipedia.org/wiki/Buddhism). This explains the main doctrines of Buddhism, it's ideas on the human mind, happiness and suffering:

4 Doctrine

In Buddhism, any person who has awakened from the "sleep of ignorance" (by directly realizing the true nature of reality), without instruction, is called a buddha.[22] If a person achieves this with the teachings of a buddha, he is called an arahant[citation needed]. Siddhartha Gautama, the Buddha, is thus only one among other buddhas before or after him. His teachings are oriented toward the attainment of this kind of awakening, also called enlightenment, Bodhi, liberation, or Nirvana.

Part of the Buddha’s teachings regarding the holy life and the goal of liberation is constituted by the "The Four Noble Truths", which focus on dukkha, a term that refers to suffering or the unhappiness ultimately characteristic of unawakened, worldly life. The Four Noble Truths regarding suffering state what is its nature, its cause, its cessation, and the way leading to its cessation. This way to the cessation of suffering is called "The Noble Eightfold Path", which is one of the fundamentals of Buddhist virtuous or moral life.

Numerous distinct groups have developed since the passing of the Buddha, with diverse teachings that vary widely in practice, philosophical emphasis, and culture. However, there are certain doctrines which are common to the majority of schools and traditions in Buddhism, though only Theravada regards all of them as central. About all Buddhists few valid generalizations are possible.[23]

The Four Noble Truths

According to the scriptures, the Buddha taught that in life there exists sorrow / suffering which is caused by desire and it can be cured (brought to cessation) by following the Noble Eightfold Path (Sanskrit: Āryāṣṭāṅgamārgaḥ , Pāli: Ariyo Aṭṭhaṅgiko Maggo). This teaching is called the Catvāry Āryasatyāni (Pali: Cattāri Ariyasaccāni), the "Four Noble Truths".

1. Suffering: Birth is suffering, aging is suffering, illness is suffering, death is suffering; union with what is displeasing is suffering; separation from what is pleasing is suffering; not to get what one wants is suffering; in brief, the five aggregates subject to clinging are suffering.
2. The cause of suffering: The desire which leads to renewed existence (rebirth) (the cycle of samsara)
3. The cessation of suffering: The cessation of desire.
4. The way leading to the cessation of suffering: The Noble Eightfold Path;

According to the scriptures, the Four Noble Truths were among the topics of the first sermon given by the Buddha after his enlightenment,[24] which was given to the five ascetics with whom he had practiced austerities, and were originally spoken by the Buddha, not in the form of a religious or philosophical text, but in the form of a common medical prescription of the time. The traditional understanding in the Theravada is that these are an advanced teaching for those who are ready for them.[25]

The Noble Eightfold Path

The eight-spoked Dharmachakra. The eight spokes represent the Noble Eightfold Path of Buddhism.
According to a saying attributed in some traditions to the Buddha, if a person does not follow the Eightfold Path, one lives one's life like a preoccupied child playing with toys in a house that is burning to the ground.[26]

The Noble Eightfold Path is the way to the cessation of suffering, the fourth part of the Four Noble Truths. This is divided into three sections: Sila (which concerns wholesome physical actions), Samadhi (which concerns the meditative concentration of the mind) and Prajñā (which concerns spiritual insight into the true nature of all things).

Sila is morality — abstaining from unwholesome deeds of body and speech. Within the division of sila are three parts of the Noble Eightfold Path:

1. Right Speech — One speaks in a non hurtful, not exaggerated, truthful way (samyag-vāc, sammā-vācā)
2. Right Actions — Wholesome action, avoiding action that would do harm (samyak-karmānta, sammā-kammanta)
3. Right Livelihood — One's way of livelihood does not harm in any way oneself or others; directly or indirectly (samyag-ājīva, sammā-ājīva)

Samadhi is developing mastery over one’s own mind. Within this division are another three parts of the Noble Eightfold Path:
1. Right Effort/Exercise — One makes an effort to improve (samyag-vyāyāma, sammā-vāyāma)
2. Right Mindfulness/Awareness — Mental ability to see things for what they are with clear consciousness (samyak-smṛti, sammā-sati)
3. Right Concentration — Being aware of the present reality within oneself, without any craving or aversion. (samyak-samādhi, sammā-samādhi)

Prajñā is the wisdom which purifies the mind. Within this division fall two more parts of the Noble Eightfold Path:
1. Right Thoughts — Change in the pattern of thinking. (samyak-saṃkalpa, sammā-saṅkappa)
2. Right Understanding — Understanding reality as it is, not just as it appears to be. (samyag-dṛṣṭi, sammā-diṭṭhi)

The word samyak means "perfect". There are a number of ways to interpret the Eightfold Path. On one hand, the Eightfold Path is spoken of as being a progressive series of stages through which the practitioner moves, the culmination of one leading to the beginning of another, whereas others see the states of the 'Path' as requiring simultaneous development. It is also common to categorize the Eightfold Path into prajñā (Pāli paññā, wisdom), śīla (Pāli sīla, virtuous behavior) and samādhi (concentration).
Bodhi


Gautama Buddha, Gandhara, northern Pakistan.

Bodhi (Pāli and Sanskrit बॊधि, lit. awakening) is a term applied in Buddhism to the specific awakening experience attained by the Buddha. When used in a generic sense, a buddha is generally considered to be a person who discovers the true nature of reality through lifetimes of spiritual cultivation, investigation of the various religious practices of his time, and meditation. This transformational discovery is called Bodhi (literally, "awakening" — more commonly called "enlightenment"). In Sino-Japanese Buddhism (Zen) this experience is called Satori.
After attainment of Bodhi, it is believed one is freed from the compulsive cycle of saṃsāra: birth, suffering, death and rebirth, and attains the "highest happiness" (Nirvana, as described in the Dhammapada). Bodhi is attained only by the accomplishment of the pāramitās (perfections), when the Four Noble Truths are fully grasped, and when all karma has reached cessation. At this moment, all greed (lobha), hatred (Pali dosa), delusion (moha), ignorance (Sanskrit avidyā, Pāli avijjā), craving (Sanskrit tṛṣṇā, Pāli taṇhā) and belief in self(ātmān, Pāli attā) are extinguished. Bodhi thus implies understanding of anātman (Pāli anatta), the absence of ego-centeredness. All schools of Buddhism recognize three types of Bodhi. They are Śrāvakabodhi (Pāli: Sāvakabodhi), Pratyekabodhi (Pāli: Paccekabodhi) and Samyaksambodhi (Pāli: Sammāsambodhi), the perfect enlightenment by which a bodhisattva becomes a fully enlightened buddha.

According to a saying attributed in some traditions to the Buddha, if a person does not follow the goal of Total Realization, one lives one's life like a preoccupied child playing with toys in a house that is burning to the ground.[27] The aspiration to attain the state of samyaksambodhi, known as the Bodhisattva ideal, is considered as the highest ideal of Buddhism.

Middle Way

The primary guiding principle of Buddhist practice is the Middle Way which was discovered by the Buddha prior to his enlightenment (bodhi). The Middle Way or Middle Path has several definitions:

1. It is often described as the practice of non-extremism; a path of moderation away from the extremes of self-indulgence and opposing self-mortification.
2. It also refers to taking a middle ground between certain metaphysical views, e.g. that things ultimately either exist or do not exist.[28]
3. An explanation of the state of nirvana and perfect enlightenment where all dualities fuse and cease to exist as separate entities (see Seongcheol).


Refuge in the Three Jewels

Acknowledging the Four Noble Truths and making the first step in the Noble Eightfold Path requires taking refuge, as the foundation of one's religious practice, in Buddhism's Three Jewels (Sanskrit: त्रिरत्न Triratna or रत्नत्रय Ratna-traya, Pali: तिरतन Tiratana).[29] Tibetan Buddhism sometimes adds a fourth refuge, in the lama. The person who chooses the bodhisattva path makes a vow/pledge. This is considered the ultimate expression of compassion.

The Three Jewels are:

• The Buddha (i.e., Awakened One). This is a title for those who attained Awakening similar to the Buddha and helped others to attain it. See also the Tathāgata and Śākyamuni Buddha. The Buddha could also be represented as the wisdom that understands Dharma, and in this regard the Buddha represents the perfect wisdom that sees reality in its true form.
• The Dharma: The teachings or law as expounded by the Buddha. Dharma also means the law of nature based on behavior of a person and its consequences to be experienced (action and reaction). It can also (especially in Mahayana Buddhism) connote the ultimate and sustaining Reality which is inseverable from the Buddha.
• The Sangha: This term literally means "group" or "congregation," but when it is used in Buddhist teaching the word refers to one of two very specific kinds of groups: either the community of Buddhist monastics (bhikkhus and bhikkhunis), or the community of people who have attained at least the first stage of Awakening (Sotapanna (pali) — one who has entered the stream to enlightenment). According to some modern Buddhists, it also consists of laymen and laywomen, the caretakers of the monks, those who have accepted parts of the monastic code but who have not been ordained as monks or nuns.

According to the scriptures, The Buddha presented himself as a model and besought his followers to have faith (Sanskrit श्रद्धा śraddhā, Pāli saddhā) in his example of a human who escaped the pain and danger of existence. The Dharma, i.e. the teaching of the Buddha, offers a refuge by providing guidelines for the alleviation of suffering and the attainment of enlightenment. The Saṅgha (Buddhist Order of monks) provides a refuge by preserving the authentic teachings of the Buddha and providing further examples that the truth of the Buddha's teachings is attainable.

In certain Mahayana sutras, the Buddha, Dharma and Sangha are viewed essentially as One: all three are seen as the eternal Buddha himself.

Many Buddhists believe that there is no otherworldly salvation from one's karma. The suffering caused by the karmic effects of previous thoughts, words and deeds can be alleviated by following the Noble Eightfold Path, although the Buddha of some Mahayana sutras, such as the Lotus Sutra, the Angulimaliya Sutra and the Nirvana Sutra, also teaches that powerful sutras such as the above-named can, through the very act of their being heard or recited, wholly expunge great swathes of negative karma.

Śīla: virtuous behavior and the precepts

Śīla (Sanskrit) or sīla (Pāli) is usually rendered into English as "behavioral discipline", "morality", or ethics. It is often translated as "precept". It is an action that is an intentional effort. It is one of the three practices (sila, samadhi, and panya) and the second pāramitā. It refers to moral purity of thought, word, and deed. The four conditions of śīla are chastity, calmness, quiet, and extinguishment, i.e. no longer being susceptible to perturbation by the passions.[citation needed]

Sīla refers to overall (principles of) ethical behavior. There are several levels of sila, which correspond to 'basic morality' (five precepts), 'basic morality with asceticism' (eight precepts), 'novice monkhood' (ten precepts) and 'monkhood' (Vinaya or Patimokkha). Lay people generally undertake to live by the five precepts which are common to all Buddhist schools. If they wish, they can choose to undertake the eight precepts, which have some additional precepts of basic asceticism.

The five precepts are not given in the form of commands such as "thou shalt not ...", but are training rules in order to live a better life in which one is happy, without worries, and can meditate well.

1. To refrain from taking life. (i.e. non-violence towards sentient life forms)
2. To refrain from taking that which is not given (i.e. not committing theft)
3. To refrain from sensual misconduct (abstinence from immoral sexual behavior)
4. To refrain from lying. (i.e. speaking truth always)
5. To refrain from intoxicants which lead to loss of mindfulness (refrain from using drugs or alcohol)
In the eight precepts, the third precept on sexual misconduct is made more strict, and becomes a precept of celibacy.
The three additional rules of the eight precepts are:
6. To refrain from eating at the wrong time (only eat from sunrise to noon)
7. To refrain from dancing, using jewelery, going to shows, etc.
8. To refrain from using a high, luxurious bed.

Vinaya is the specific moral code for monks. It includes the Patimokkha, a set of 227 rules in the Theravadin recension. The precise content of the vinayapitaka (scriptures on Vinaya) differ slightly according to different schools, and different schools or subschools set different standards for the degree of adherence to Vinaya. Novice-monks use the ten precepts, which are the basic precepts for monastics.
In Eastern Buddhism, there is also a distinctive Vinaya and ethics contained within the Mahayana Brahmajala Sutra (not to be confused with the Pali text of that name) for Bodhisattvas, where, for example, the eating of meat is frowned upon and vegetarianism is actively encouraged (see vegetarianism in Buddhism).

Samadhi/Bhāvana (Meditative cultivation)

In the language of the Noble Eightfold Path, samyaksamādhi is "right concentration". The primary means of cultivating samādhi is meditation. Almost all Buddhist schools agree that the Buddha taught two types of meditation, viz. samatha meditation (Sanskrit: śamatha) and vipassanā meditation (Sanskrit: vipaśyanā). Upon development of samādhi, one's mind becomes purified of defilement, calm, tranquil, and luminous.

Once the meditator achieves a strong and powerful concentration (jhāna, Sanskrit ध्यानम् dhyāna), his mind is ready to penetrate and gain insight (vipassanā) into the ultimate nature of reality, eventually obtaining release from all suffering. The cultivation of mindfulness is essential to mental concentration, which is needed to achieve insight.

Samatha Meditation starts from being mindful of an object or idea, which is expanded to one's body, mind and entire surroundings, leading to a state of total concentration and tranquility (jhāna) There are many variations in the style of meditation, from sitting cross-legged or kneeling to chanting or walking. The most common method of meditation is to concentrate on one's breath, because this practice can lead to both samatha and vipassana.

In Buddhist practice, it is said that while samatha meditation can calm the mind, only vipassanā meditation can reveal how the mind was disturbed to start with, which is what leads to jñāna (Pāli ñāṇa knowledge), prajñā (Pāli paññā pure understanding) and thus can lead to nirvāṇa (Pāli nibbāna).

Prajñā (Wisdom)

Prajñā (Sanskrit) or paññā (Pāli) means wisdom that is based on a realization of dependent origination, The Four Noble Truths and Noble Eightfold Path. Prajñā is the wisdom that is able to extinguish afflictions and bring about bodhi. It is spoken of as the principal means, by its enlightenment, of attaining nirvāṇa, through its revelation of the true nature of all things. Prajñā is also listed as the sixth of the six pāramitās.

Initially, prajñā is attained at a conceptual level by means of listening to sermons (dharma talks), reading, studying and sometimes reciting Buddhist texts and engaging in discourse. The Buddha taught dharma to his disciples mainly through the mean of discourse or sermon,[citation needed] many attaining bodhi upon hearing the Buddha's discourse.

Once the conceptual understanding is attained, it is applied to daily life so that each Buddhist can verify the truth of the Buddha's teaching at a practical level. Lastly, one engages in insight (vipassanā, Sanskrit vipaśyanā) meditation (Citation needed) to attain such wisdom at intuitive level. It should be noted that one could theoretically attain bodhi at any point of practice, while listening to a sermon, while conducting business of daily life or while in meditation.