Kapalabhati (pronounced KAH-pah-lah-BAH-tee) (aka Kapalbhati, or Bhalabhai in the Gherand Samhita), is an important part of Shatkarma (sometimes known as Shatkriya), the yogic system of body cleansing techniques. It is intended mainly to the cleaning of the cranial sinuses but has many other effects, according to the Gherand Samhita and other sources. The Technique of Kapalabhati involves short and strong forceful exhalations and inhalation happens automatically. There are three forms of Kapalabhati:
Vatakrama kapalabhati, a practice similar to Bhastrika, a technique of Pranayama, except that exhalation is active while inhalation is passive, the opposite of normal breathing.
Vyutkrama kapalabhati, a practice similar to Jala neti, it involves sniffing water through the nostrils and letting it flow down into the mouth and then spitting it out.
Sheetkrama kapalabhati, can be considered the reverse of Vyutkrama kapalabhati, in which water is taken through the mouth and then expelled through the nose.
Definition courtesy Wikipedia.