Quietude, also known as shamata or samatha (Sanskrit), shi-ne (Tibetan), samatha (Pali), and calm abiding, is defined as:

The single-mindedness that is imbued with the exceptional bliss of practiced ease due to deep, single-pointed meditation on its object.

Shamata is considered the mental platform necessary to achieve insight into reality and the direct experience of emptiness or ultimate reality.  Shamata is characterized by pleasant physical sensations, effortlessness in holding one’s meditational object in awareness, the ability to move fluidly and intentionally between objects and the occurrence of this state as soon as one sits down to meditate.  It is a bright, vivid, and exceptionally calm state and not trance like in anyway.

Meditators progress towards shamata by passing through nine stages starting with complete scatter-mind, moving to the ability to hold the object in awareness at all times, then the disappearance of narrative or discursive thoughts and increasing calm until finally shamata is achieved.