Kumbhaka is the retention of the breath in the hatha yoga practice of pranayama. It has two types, accompanied (by breathing) whether after inhalation or after exhalation, and, the ultimate aim, unaccompanied. That state is kevala kumbhaka, the complete suspension of the breath for as long as the practitioner wishes.
Kumbhaka is the retention of the breath in pranayama, either after inhalation, the inner or Antara Kumbhaka, or after exhalation, the outer or Bahya Kumbhaka (also called Bahir Kumbhaka). According to B.K.S. Iyengar in Light on Yoga, kumbhaka is the "retention or holding the breath, a state where there is no inhalation or exalation".
Kevala Kumbhaka, when inhalation and exhalation can be suspended at will, is the extreme stage of Kumbhaka "parallel with the state of Samadhi", or union with the divine, the last of the eight limbs of yoga, attained only by continuous long term pranayama and kumbhaka exercises. The 18th century Joga Pradipika states that the highest breath control, which it defines as inhaling to a count (mātrā) of 8, holding to a count of 19, and exhaling to a count of 9, confers liberation and Samadhi.
The Yoga Institute recommends sitting in a meditative posture such as Sukhasana for Kumbhaka practice. After a full inhalation for 5 seconds, it suggests retaining the air for 10 seconds, exhaling smoothly, and then taking several ordinary breaths. It recommends five such rounds per pranayama session, increasing the time of retention as far as is comfortable by one second each week of practice.
The yoga scholar Andrea Jain states that while pranayama in modern yoga as exercise consists of synchronising the breath with movements (between asanas), in ancient texts like the Bhagavad Gita and the Yoga Sutras of Patanjali, pranayama meant "complete cessation of breathing", for which she cites Bronkhorst 2007. The Yoga Sutras state:
[D]istractions ... act as barriers to stillness. ... One can subdue these distractions by ... pausing after breath flows in or out.
With effort relaxing, the flow of inhalation and exhalation can be brought to a standstill; this is called breath regulation.
According to the scholar-practitioner of yoga Theos Bernard, the ultimate aim of pranayama is the suspension of breathing, "causing the mind to swoon". Swami Yogananda writes, "The real meaning of Pranayama, according to Patanjali, the founder of Yoga philosophy, is the gradual cessation of breathing, the discontinuance of inhalation and exhalation".
The yoga scholars James Mallinson and Mark Singleton write that "pure breath-retention" (without inhalation or exhalation) is the ultimate pranayama practice in later hatha yoga texts. They give as an example the account in the c. 13th century Dattātreyayogaśāstra of kevala kumbhaka (breath retention unaccompanied by breathing). They note that this is "the only advanced technique" of breath-control in that text, stating that in it the breath can be held "for as long as one wishes". The Dattātreyayogaśāstra states that kevala kumbhaka gives magical powers, allowing the practitioner to do anything:
Once unaccompanied [kevala] breath-retention, free from exhalation and inhalation, is mastered, there is nothing in the three worlds that is unattainable.
Mallinson and Singleton note that sahita kumbhaka, the intermediate state which is still accompanied (the meaning of sahita) by breathing, was described in detail. They write that the Goraksha Sataka describes four sahita kumbhakas, and that the Hatha Yoga Pradipika describes another four. They point out, however, that these supposed kumbhakas differ in their styles of breathing, giving the example of the buzzing noise made while breathing in bhramari.