“The six kinds of duties are: Dhauti, Basti, Neti, Trataka, Nauti and Kapala Bhati. These are called the six actions.
These six kinds of actions which cleanse the body should be kept secret. They produce extraordinary attributes and are performed with earnestness by the best Yogis and Yoginis.”
(Hatha Yoga Pradipika 2:22 -23)

Sat karma (sometimes known as Sat kriya) is a compound word consisting of two components: 'shat' meaning 'six' and 'karma' meaning 'art' or 'process'. The word 'kriya' or 'karma' is used in Hatha Yoga in a special technical sense regarding the techniques of cleaning. Dhauti, basti, neti, trataka, nauli and kapalbhati are the six traditionally known processes.

'Hatha Yoga Pradipika' is not the only authentic yoga work, which explains exactly the six cleansing practices. 'Pranatoshani' text refers to five purifications practices. Besides these texts, a vernacular treatise, 'Bhakti Sagram' of Charana Das describes in detail the shat karmas and in addition mentions four mere, which it does not describe. The 'Gherand Samhita' and 'Hatha Yoga Samhita' describes twenty-one such practices, albeit under six broad headings. Also the 'Shatkarma Samgraha' describes no less than forty-six such sat karmas, such as vamana, vireehana, gandusha, udgara, and raktasrava.

Yoga gives as much importance to certain internal cleansing processes in combination with asana and pranayama practice, sandana. Without regular cleansing of the system one cannot gain maximum benefit from yoga practices. Without purification of the body one will not be ready for the higher practices of yoga.

Body cleansing is brought about by the practice of the shat karmas or six purification techniques, which are very important from the point of view of physical and mental health. These simple techniques are also highly valuable in healing internal disorders. They also bring clarity and harmony to the mind.

The sat karmas affect and activate almost all of the vital systems in the body, especially the digestive, respiratory, circulatory and nervous systems. Every individual organ of importance, like the mouth, food pipe, stomach, intestines, colon, lungs, eyes and ears, receives equal attention. These purificatory processes are both preventive and curative.

According to Ayurveda there are three humors in the body: kapha (mucus), pita (bile), and vata (wind) and they are called tridasha. A balanced proportion of these three facilitates body functions, but if there is excess of one and shortage of another, ailments develop due to overheating or not enough heat in the body. So, before commencing pranayama, any imbalance in the doshas should be removed.

There are six main groups of satkarmas or yogic cleansers  and each of these groups contains more than one practice, such as jala neti, vaman dhauti (or kunjal kriya), moola shodhana etc.

 The six Sat Karmas:

1. DHAUTI- Yogic cleansing of the digestive tract.

a. Antar ( internal )Dhauti -This further divided into -
   Vatsara Dhauti (Expelling air through anus)
   Varisara Dhauti (Evacuating a large quantity of water through the bowels)
   Vahnisara Dhauti (rapid expanse/contraction of the abdomen)
   Bahiskrita Dhauti (washing the rectum in the hands)

b. Hrida(cardiac) Dhauti - It has 3 kinds of practices -
   Danda Dhauti (Inserting soft banana stem in the stomach)
   Vastra Dhauti (Swallowing a long thin strip of cloth)
   Vaman Dhauti (Regurgirating the contents of the stomach

2. BASTI- Yogic colon cleaning
   1.   Jala (water) Basti (Water is sucked in the large intestine through the anus and expelled)
   2. Sthala (Dry) Basti (Air is sucked in the large intestine through the anus and expelled)

3. NETI - Yogic nasal cleaning
   1.   Sutra (thread) Neti (passing a soft thread through the nose)
   2.   Jala (water) Neti (passing warm saline water through the nose)
   3a  Ghrita (ghee) Neti (passing clarified butter through the nose)
   3b  Dugdha (milk) Neti (passing of milk through the nose

4. TRATAKA- Yogic Concentrated Gazing
   1.   Bahiranga (external) Trataka
   2.   Antaranga (internal) Trataka

5. NAULI – Yogic abdominal massage
   1.   Madhyama Nauli (the isolated contraction of the central muscles of the abdomins)
   2.   Vama Nauli (the isolated contraction of the left part of the central muscles of the abdomen)
   3.   Dakshina Nauli (the isolated contraction of the right part of the central muscles of the abdomen)
   4.   Nauli kriya (the circular movement of the central muscles of the abdomen)

6. KAPALBHATI – yogic purification and vitalisation of the frontal lobes.    
   1. Vatkrama Kapalbhati (similar to bhastrika pranayama)
   2. Vyutkrama Kapalbhati (sucking water in through the nose and expelling it through the mouth)
   3. Sheetkrama Kapalbhati

These yoga cleansing practices are very powerful practices and should be learned under the guidance of an experienced yoga or ayurveda teacher.  Sat κarmas never can be learned from books or taught by inexperienced people. The experienced teacher shall be able to guide you which technique is best suited to your body type.  One may think that he has the capacity to teach but actually he may not have adequate experience or knowledge to guide ethers proficiently. Also out of the above techniques mentioned some of them are advanced, and should be done after perfecting the easier and basic ones.  The sat karmas if practiced unnecessarily, will not be so effective when genuinely required.

The ancient yoga texts said to be 'secret' practices and the student must be personally instructed how to perform them and how often, according to individual need. For this, a qualified and experienced teacher is essential.  No wonder these practices were treated with great esteem and respect by the yogis who perfected them and knew about their power.

When the different systems of the body have been purified, the overall result is that energy can flow through the body  freely. One's capacity to work, think, digest, taste, feel, experience, etc., increases and greater awareness develops. It is no wonder that the yogis who have attained perfection consider the sat karmas with great esteem.