'Pranayama' is the fourth stage in Pathanjali's eight stage Yoga discipline.  Two Sanskrit words are combined in the word 'Pranayama' - Prana and Ayama. 'Prana' means life or life force. 'Ayama' means development or control. Therefore Pranayama is the development and control of life force. It is a form of breathing exercise, very important in yoga. It goes along with the asanas or exercise. 

Breath is the life force that sustains life. Nobody can survive more than a few minutes without air. When the breath stops, life ends. The Forefathers of Yoga developed a special system- 'Pranayama' to increase, develop and control this life force. Normal breathing use only a fraction of our potential respiratory capacity. Pranayama helps to control this life force in a superior and extra ordinary way to reap maximum benefits. 

There are various types of Pranayama. Some of the popular forms are Ujjayee, Shitali, Viloma,  Kapalabhati, Anuloma, Suryabhedana,  Bhastrika etc. There are variations in performing different Pranayamas. Some of them can be done in a sitting position while others in a standing line or sitting position. Some of the Pranayama are difficult and complicated to perform while others are easy.

Pranayama can be mastered only gradually. It may take months or even years before the practitioner mind becomes receptive to the regulated flow of breath and he experiences the full benefits of pranayama. Proper practice of pranayama can control almost any disease but improper practice may give rise to all sorts of respiratory ailments. So one should take care to acquire control over his breath gradually.