There are four main bandhs.  Bandhs may be termed locks for the purpose of understanding.  These bandhs are used to undo the knots, which impede the movement of the Kundalni.    These bandhs are known as Jalandhar, Moola, Uddiyana and Maha Bands. 

(a)     Jalandhar Bandh.   Sit in Padmaasana or Siddhasana; those who cannot do this may do this exercise standing.   Place the palm on the knees, slowly inhale and expand the chest.   After inhalation retain the breath, bend the head forward and press the chin on the chest, retain the breath for a while do not strain.   Release the breath from both the nostrils.   Do not breathe during the chin lock, open the lock by raising the head and then exhale.  Persons suffering from cervical problems are not to perform this exercise.  People with heart problems and high blood pressure are also to refrain from this bandh.  This bandh is ideally performed at the end of each pranayama.    This bandh is beneficial for the respiratory system and the circulatory system.    The practice of this bandh helps in relieving stress and produces a feeling of goodness and relaxation.   Scriptures also reveal that those who practice this bandh do not waste nectar released during meditation. 

(b)   Moola Bandh.   Sit in siddha asana so that pressure is exerted in the groin region. Close the eyes, focus the attention on the groin area, breathe normally and contract the area by pulling the muscles of the pelvic region towards the back.   Pull the muscles rhythmically and evenly.   Relax the muscles slowly and then exhale.   This bandh should be learnt under supervision.   This bandh energizes the complete body; it is of great benefit for the body and mind.   It helps in relieving of constipation, piles, prostatitis, and anal fissures and tones up the complete sexual system in the both male and female bodies.  It is also beneficial in cases of asthma, bronchitis and arthritis.

(c)    Uddiyana Bandh.   Stand straight with the feet about 2 feet apart.   Bend forward and exhale the complete air from the lungs through the mouth.    Place the palms just above the knees, the fingers can point down wards or towards each other.   Contract the abdomen backwards.    Straighten the legs this will draw the abdomen inward towards the spine.   Remain in this posture in due comfort.   Release the bandh and slowly inhale through the nostrils.    Remain in the position and repeat the practice at least three times.   Ten rounds can be performed.   Pregnant ladies and people with hiatus hernia and umbilical hernia should not practice this band.   Also those suffering from cardiac diseases and hypertension are to abstain from this exercise.  Other than chronic abdominal ailments it is a boon for all types of problems of the stomach including diabetes.    It helps in awakening of the Kundalni Shakti.