Samatha (Pāli; Sinhala: සමථ; Chinese: 止; pinyin: zhǐ), "calm," "serenity," "tranquillity of awareness," and vipassanā (Pāli; Sinhala විදර්ශනා (Vidarshana); Sanskrit vipaśyanā), literally "special, super (vi-), seeing (-passanā)", are two qualities of the mind developed in tandem in Buddhist practice. In the Pali Canon and the Āgama they are not specific practices, but elements of "a single path," and "fulfilled" with the development (bhāvanā) of sati ("mindfulness") and jhana/dhyana ("meditation") and other path-factors. While jhana/dhyana has a central role in the Buddhist path, vipassanā is hardly mentioned separately, but mostly described along with samatha.

The Abhidhamma Pitaka and the commentaries describe samatha and vipassanā as two separate techniques, taking samatha to mean concentration-meditation, and vipassana as a practice to gain insight. In the Theravada-tradition, vipassanā is defined as a practice that seeks "insight into the true nature of reality", defined as anicca "impermanence", dukkha "suffering, unsatisfactoriness", anattā "non-self", the three marks of existence. In the Mahayana-traditions vipassanā is defined as insight into śūnyatā "emptiness" and Buddha-nature.

In modern Theravada, the relation between samatha and vipassanā is a matter of dispute. Meditation-practice was reinvented in the Theravada tradition in the 18th-20th century, based on contemporary readings of the Satipaṭṭhāna sutta, the Visuddhimagga, and other texts, centering on vipassana and 'dry insight' and downplaying samatha. Vipassana became of central importance in the 20th century Vipassanā movement favoring vipassanā over samatha. Some critics point out that both are necessary elements of the Buddhist training, while other critics argue that dhyana is not a single-pointed concentration exercise.