In Indian Yoga therapy, Pranayama holds a place of special significance. Pranayama occupies second place in Hatha Yoga while it constitutes the fourth step of Patanjali`s Ashtanga yoga. A serious student of yoga is expected to start practice of Pranayama when he or she becomes well versed in yoga asanas, i.e., when a stage of asanjaya is achieved so that one can sit for hours together, steadily and comfortably.

The word Pranayama is formed by two words i.e., `prana` and `ayama.` `Prana` means life force, which provides energy to different organs (including mind) and also controls many vital life processes, like respiration and circulation of blood. `Ayama,` on the other hand, signifies the voluntary effort to control and direct this prana. Breathing is one of the vital activities governed by prana. This is the only pranic activity which the human beings can voluntarily regulate. Secondly, the breathing system is linked with the nervous system (base of the mental activity) on one hand and the mind (consciousness) on the other. Yoga has taken best advantage of this situation, considering that the mind could be controlled effectively with the voluntary regulation over breathing. This is expected to manage the materialistic inclinations and instincts of `chitta` (super consciousness).

Therefore, Pranayama essentially becomes a process by which the mind is controlled by voluntary regulation of the breathing. Hence, Pranayama is a voluntary and temporary pause in the movement of the breath. From yogic point of view it is a path that connects one`s physical existence and the spiritual consciousness.

The yoga sutras by Patanjali states: `Tasminsati shvasaprashvasayor gativichchedah pranayamah.` This quote narrates that the pause, brought in the movement of inhalation and exhalation, is nothing but pranayama. Rishi Patanjali has explained four types of pranayama on the basis of the nature of the `pause` (stambhavrutti) that is a temporary suspension of breath.

These types are:
(1) Pause after or at the end of the prolonged (deergha) and very slow (manda) exhalation (prashwas).
(2) Pause after or at the end of deep and prolonged inhalation (shwas).
(3) Pause is brought any time one wants to bring for a considerable time. It may be somewhere in between the usual inhalation or exhalation. This is a prolongation of a break in the breathing (stambhavritti).
(4) The practitioner experiences pause at any time without his voluntary efforts, after a long practice of above three types of pauses.

As per yogic literature, when breath is held after exhalation, it is known as Bahya kumbhaka; when the breathing is stopped after inhalation, it is known as Abhyantara kumbhaka while the fourth type of pause as mentioned above which comes automatically after a long practice of Pranayama, is known as Keval kumbhaka. Effect of each type of Pranayama is also different on the physical, mental and on the spiritual levels.

According to Patanjali, a slightest change brought in the normal speed of breathing is Pranayama. Also systematically controlled and prolonged inhalations and exhalations constitute Pranayama. Obviously to do this a voluntary control is necessary. In normal breathing also, there is a pause between inhalation and exhalation that may be only for a few milliseconds. Therefore voluntary control brought on any one of the three, i.e., inhalation, exhalation, the pause, or on all three, will be called Pranayama.