Pranayama is divided from two Sanskrit words 'Prana' and 'Ayama'. Prana means universal life force energy and Ayama means elongation or to regulate. Pranayama are breathing exercises which clear the physical and emotional obstacles in our body to free the breath and so the flow of Prana - life energy. Through regular and sustained practise of Pranayama you can supercharge your whole body. 

Acceding to Patanjali's eight fold path - fourth step is;

Yoga after having the physical discipline, proceeds to teach how to regulate and control the Prana. It's called the discipline of prana or bio-energy. Actually Prana is the vital force through which life is sustained. 

In the Yoga Sutras some commentators used the term prana as meaning the breath. Actually  Prana is neither the breath nor the air. It would rather be the bio-energy that causes the motion of the lungs, that the vital element in the Universe, and life is sustained exclusively because of it.


Practice of mine breathing exercises is being recommended. They can be divided into tow main groups according to their specific purpose: 
PRANAYAMA 1 - Deep Yogic Breathing
PRANAYAMA 2 - Intercostal Breathing 
PRANAYAMA 3 - Clavicular Breathing 
PRANAYAMA 4 - Diaphragmatic Breathing 
PRANAYAMA 5 - Suspension of Breathing (Shunyaka)
PRANAYAMA 6 - Complete inhalation (Puraka) 
PRANAYAMA 7 - Retention of Breathing (Kumbhaka) 
PRANAYAMA 8 - Complete exhalation (Rechaka)
PRANAYAMA 9 - Alternate Nostril Breathing (Anuloma Viloma)
A) Pranayama 1 to 4 aim at equalisation of breathing and strengthening of the respiratory muscles;
B) Pranayama 5 to 9 aims at suspension, prolongation of inhalation, retention, exhalation of the breath and alternate nostril breathing.