Three marks of existence

In Buddhism, the three marks of existence are three characteristics (Pali: tilakkhaṇa; Sanskrit: त्रिलक्षण trilakṣaṇa) of all existence and beings, namely anicca (impermanence), dukkha (commonly translated as "suffering" or "cause of suffering", "unsatisfactory", "unease"), and anattā (without a lasting essence). The concept of humans being subject to delusion about the three marks, this delusion resulting in suffering, and removal of that delusion resulting in the end of dukkha, is a central theme in the Buddhist Four Noble Truths and Noble Eightfold Path.

Description
There are different lists of the "marks of existence" found in the canons of the early Buddhist schools.

Three marks
In the Pali tradition of the Theravada school, the three marks are: The northern Buddhist Sarvāstivāda tradition meanwhile has the following in their Samyukta Agama:
 * sabbe saṅkhārā aniccā – all saṅkhāras (conditioned things) are impermanent
 * sabbe saṅkhārā dukkhā – all saṅkhāras are unsatisfactory, imperfect, unstable
 * sabbe dhammā anattā – all dharmas (conditioned or unconditioned things) have no unchanging self or soul
 * All conditioned things are impermanent (sarvasaṃskārā anityāḥ)
 * All dharmas are non-self (sarvadharmā anātmānaḥ)
 * Nirvāṇa is calm (śāntaṃ nirvāṇam)

Four marks
In the Ekottarika-āgama and in Mahayana sources like the Yogācārabhūmi-Śāstra and The Questions of the Nāga King Sāgara (Sāgaranāgarājaparipṛcchā) however, four characteristics or “four seals of the Dharma” (Sanskrit: dharmoddāna-catuṣṭayaṃ or catvāri dharmapadāni, Chinese: 四法印) are described instead of three:
 * All compounded phenomena are impermanent (anitya)
 * All contaminated phenomena are without satisfaction (duḥkha)
 * All phenomena are without self (anātman)
 * Nirvana is peaceful/peace (śānta/śānti)

Anicca
Impermanence (Pali: anicca, Sanskrit: anitya) means that all things (saṅkhāra) are in a constant state of flux. Buddhism states that all physical and mental events come into being and dissolve. Human life embodies this flux in the aging process and the cycle of repeated birth and death (Samsara); nothing lasts, and everything decays. This is applicable to all beings and their environs, including beings who are reborn in deva (god) and naraka (hell) realms. This is in contrast to nirvana, the reality that is nicca, or knows no change, decay or death.

Dukkha
Dukkha (Sanskrit: duhkha) means "unsatisfactory", commonly translated as "suffering", "pain". Mahasi Sayadaw calls it 'unmanagable, uncontrollable'.

As the First Noble Truth, dukkha is explicated as the physical and mental dissatisfaction of changing conditions as in birth, aging, illness, death; getting what one wishes to avoid or not getting what one wants; and "in short, the five aggregates of clinging and grasping" (skandha). This, however, is a different context, not the Three Marks of Existence, and therefore 'suffering' may not be the best word for it.

The relationship between the three characteristics is explained in the Pali Canon as follows: What is anicca is dukkha. What is dukkha is anatta (Samyutta Nikaya.Vol4.Page1).
 * "That which is impermanent is dukkha (i.e. it cannot be made to last). That which is dukkha is not permanent."

Anatta
Anatta (Sanskrit: anatman) refers to there being no permanent essence in any thing or phenomena, including living beings.

While anicca and dukkha apply to "all conditioned phenomena" (saṅkhārā), anattā has a wider scope because it applies to all dhammās without the "conditioned, unconditioned" qualification. Thus, nirvana too is a state of without Self or anatta. The phrase "sabbe dhamma anatta" includes within its scope each skandha (group of aggregates, heaps) that compose any being, and the belief "I am" is a conceit which must be realized to be impermanent and without substance, to end all dukkha.

The anattā doctrine of Buddhism denies that there is anything permanent in any person to call one's Self, and that a belief in a Self is a source of dukkha. Some Buddhist traditions and scholars, however, interpret the anatta doctrine to be strictly in regard to the five aggregates rather than a universal truth, despite the Buddha affirming so in his first sermon. Religious studies scholar Alexander Wynne calls anattā a "not-self" teaching rather than a "no-self" teaching.

Application
In Buddhism, ignorance (avidyā, or moha; i.e. a failure to grasp directly) of the three marks of existence is regarded as the first link in the overall process of saṃsāra whereby a being is subject to repeated existences in an endless cycle of dukkha. As a consequence, dissolving that ignorance through direct insight into the three marks is said to bring an end to saṃsāra and, as a result, to that dukkha (dukkha nirodha or nirodha sacca, as described in the third of the Four Noble Truths).

Gautama Buddha taught that all beings conditioned by causes (saṅkhāra) are impermanent (anicca) and suffering (dukkha), and that not-self (anattā) characterises all dhammas, meaning there is no "I", "me", or "mine" in either the conditioned or the unconditioned (i.e. nibbāna). The teaching of three marks of existence in the Pali Canon is credited to the Buddha.