Sampajañña means "clear comprehension," "clear knowing," "constant thorough understanding of impermanence," "fully alert" or "full awareness," as well as "attention, consideration, discrimination, comprehension, circumspection."

Sampajañña is a Pali term used in Theravada

Theravada

Theravada ; literally, "the Teaching of the Elders" or "the Ancient Teaching", is the oldest surviving Buddhist school. It was founded in India...

 sutta

Sutra

Sūtra is an aphorism or a collection of such aphorisms in the form of a manual. Literally it means a thread or line that holds things together and is derived from the verbal root siv-, meaning to sew , as does the medical term...

s; the equivalent Sanskrit term samprajaña is found in Sanskrit texts employed (in translation) by a variety of meditation teachers such as Zen

Zen

Zen is a school of Mahāyāna Buddhism founded by the Buddhist monk Bodhidharma. The word Zen is from the Japanese pronunciation of the Chinese word Chán , which in turn is derived from the Sanskrit word dhyāna, which can be approximately translated as "meditation" or "meditative state."Zen...

 master Thich Nhat Hanh and in the Tibetan tradition.

From the Pali Canon

Clear comprehension is most famously invoked by the Buddha in tandem with mindfulness practice in the Satipatthana Sutta

Satipatthana Sutta

The Satipaṭṭhāna Sutta and the Mahāsatipaṭṭhāna Sutta are two of the most important and widely studied discourses in the Pali Canon of Theravada Buddhism...

:

Herein (in this teaching) a monk lives contemplating the body in the body, ardent, clearly comprehending and mindful, having overcome, in this world, covetousness and grief; he lives contemplating feelings in feelings, ardent, clearly comprehending and mindful, having overcome, in this world, covetousness and grief; he lives contemplating consciousness in consciousness, ardent, clearly comprehending and mindful, having overcome, in this world, covetousness and grief; he lives contemplating mental objects in mental objects, ardent, clearly comprehending and mindful, having overcome, in this world, covetousness and grief.

Clear comprehension develops out of mindfulness of breathing (ānāpānasati

Anapanasati

Ānāpānasati , meaning 'mindfulness of breathing' , is a form of Buddhist meditation now common to the Tibetan, Zen, Tiantai, and Theravada schools of Buddhism, as well as western-based mindfulness programs.According to tradition, Anapanasati was...

) and is subsequently present in tandem with mindfulness for all four satipathanas.

Canonical commentary

While the nikaya

Nikaya

Nikāya is a word of meaning "collection", "assemblage", "class" or "group" in both Pāḷi and Sanskrit. It is most commonly used in reference to the Buddhist texts of the Sutta Piṭaka, but can also refer to the monastic divisions of Theravāda Buddhism...

s do not elaborate on what the Buddha meant by sampajañña, the Pali commentaries

Pali literature

Pali literature is concerned mainly with Theravada Buddhism, of which Pali is the traditional language.- India :Main article: Pali CanonThe earliest and most important Pali literature constitutes the Pali Canon, the scriptures of Theravada...

 analyze it further in terms of four contexts for one's comprehension:

• purpose (Pāli: sātthaka): refraining from activities irrelevant to the path
  Noble Eightfold Path
  The Noble Eightfold Path , is one of the principal teachings of the Buddha, who described it as the way leading to the cessation of suffering and the achievement of self-awakening. It is used to develop insight into the true nature of phenomena and to eradicate greed, hatred, and delusion...
  
  .
• suitability (sappāya): pursuing activities in a dignified and careful manner.
• domain (gocara): maintaining sensory restraint consistent with mindfulness.
• non-delusion (asammoha): seeing the true nature of reality (see three characteristics and anatta
  Anatta
  In Buddhism, anattā or anātman refers to the notion of "not-self." In the early texts, the Buddha commonly uses the word in the context of teaching that all things perceived by the senses are not really "I" or "mine," and for this reason one should not cling to them.In the same vein, the Pali...
  
  ).

Critical to Right Mindfulness' purpose (Nyanaponika)

In a correspondence between Bhikkhu Bodhi

Bhikkhu Bodhi

Bhikkhu Bodhi , born Jeffrey Block, is an American Theravada Buddhist monk, ordained in Sri Lanka and currently teaching in the New York/New Jersey area...

 and B. Alan Wallace

B. Alan Wallace

B. Alan Wallace is an American author, translator, teacher, researcher, interpreter, and Buddhist practitioner interested in the intersections of consciousness studies and scientific disciplines such as psychology, cognitive neuroscience, and physics...

, Bodhi described Ven. Nyanaponika Thera

Nyanaponika Thera

Nyanaponika Thera or Nyaniponika Mahathera was a German-born Sri-Lanka-ordained Theravada monk, co-founder of the Buddhist Publication Society, contemporary author of numerous seminal Theravada books, and teacher of contemporary Western Buddhist leaders such as Bhikkhu Bodhi.-Chronology:*1901: born...

's views on "right mindfulness" and as follows,

... I should add that Ven. Nyanaponika himself did not regard “bare attention” as capturing the complete significance of , but as representing only one phase, the initial phase, in the meditative development of right mindfulness. He held that in the proper practice of right mindfulness, sati has to be integrated with , clear comprehension, and it is only when these two work together that right mindfulness can fulfill its intended purpose.

Use day and night (Nhat Hanh)

Vietnamese Zen master, Thich Nhat Hanh, has written with regards to the aforementioned verse in the Satipatthana Sutra, on the topic of sampajañña, the following,

This exercise is the observation and awareness of the actions of the body. This is the fundamental practice of the monk. When I was first ordained as a novice forty-eight years ago, the first book my master gave me to learn by heart was a book of gathas to be practised while washing your hands, brushing your teeth, washing your face, putting on your clothes, sweeping the courtyard, relieving yourself, having a bath, and so on.

... If a novice applies himself to the practice of [this] ... exercise, he will see that his everyday actions become harmonious, graceful, and measured. Mindfulness becomes visible in his actions and speech. When any action is placed in the light of mindfulness, the body and mind become relaxed, peaceful, and joyful. [This] ... exercise is one to be used day and night throughout one's entire life.