Kryas (cleansing practices)
Classic yoga texts, such as the Hatha Yoga Pradipika, describe six kryas. They are:
- Neti (cleansing the nose)
- Trataka (candle gazing, cleanses the eyes)
- Nauli (abdominal churning, strengthens the digestive fire)
- Kapalabati (sharp abdominal breathing, cleanses the lungs)
- Vasti (cleansing of the large intestine)
- Dauti (cleansing of the stomach)
Only the first two are described here.
Nauli and Kabalabati are powerful practices which are best learned directly from a competent teacher.
Here's a link to a good Youtube video explaining Kapalabati
Vasti and Dauti are highly specialised practices that are rarely taught.