As per Hatha Yoga Pradipika, Kriyas are cleaning techniques. It is used to purify the body and mind. Thus, it opens the pathways of body, the nadis (energy channels) of energetic body and mind. So, these are yogic kriyas to clean various internal organs of the body.
These Kiryas are more popularly called Shat Karmas. Shat means six and karma means action, as they are six in number. I would like to mention the simplest practices in each of them, so that it does not seem too difficult.
1. Neti – Jala Neti Kriya is the most popularly technique for Nasal cleansing. This technique helps to treat sinus infections, allergies, headaches and even stress. The other Neti options are instead of water, Milk, Ghee or soft string is used.
2. Dhauti – Vaman Dhauti (Kunjal) Kriya can be practiced to clean the intestine by vomiting water. It washes up the entire track starting from mouth to the digestive path at the beginning of small intestines, that is mouth, esophagus. Shankha Prakshalana is advanced practice which also uses specific yoga asanas. This kriya helps to treat cases of constipation, gastritis, dyspepsia, indispositions of the stomach and spleen.
3. Basti – This kriya is slighly advance, in this process colon is cleaned. Jala Basti and Sthula Basti are most commonly used practice. It cures Pleeha, Urinary disorders and digestion disorders.
4. Trataka – It is a process of looking at a fixed point of your choice with full concentration. Usually a lighted candle is used for this kriya. It gives better concentration power and cures the ailments pertaining to the eyes. It helps quickly in short sighted.
5. Nauli –In this Kriya, abdominal is churned. It tones the abdomen and intestines, aiding both digestion and elimination. It stimulates the digestive fire, helps to remove the toxins, increasing digestive fire. Before doing this Kriya, Uddiyana Bandha must be learned and perfected.
6. Kapalbhati – It literally means Skull Shining Breath. Some teachers teach this kriya as pranayama but technically it is called Kriya. It helps in cleaning, invigorating, warming, prevents illness and allergies.