Zazen is Japanese for "seated meditation" and is the heart of Zen practice. The word joins za, to sit, and zen, meditation. In a Zen temple it is done at set times each day, usually facing a wall or the center of the room, in periods of around thirty to forty minutes.
The form is simple. You sit upright and still, on a cushion or a chair, with the eyes half open and resting on the floor ahead. Attention rests on the breath, often counted from one to ten, or on a koan, or simply on being present with no object at all.
Zazen is not treated as a technique for becoming calm, though calm may come. Many teachers describe the sitting itself as the point: an expression of awareness, not a means to something else.