Wikipedia
Shirshasana
Sirsasana, Shirshasana (; ; IAST: Śīrṣāsana), Sirshasana, or Headstand is an asana.
In the Supported Headstand (Salamba Sirasana), the body is completely inverted, and held upright supported by the forearms, while the crown of the head rests lightly on the floor.
Sirsasana is nicknamed "king" of all the asanas.
A variety of other asanas can be used to build the upper body strength and balance required for Sirsasana.