曹洞宗
is a Japanese translation of a Chinese term for "zazen" introduced by Rujing, a monk of the Caodong school of Zen Buddhism, to refer to a practice called "Silent Illumination", or "Serene Reflection", by previous Caodong masters. In Japan, it is associated with the Soto school. Unlike many other forms of meditation, shikantaza does not require focused attention on a specific object (such as the breath); instead, practitioners "just sit" in a state of conscious awareness.