Consciousness, at its simplest, is awareness of internal and external existence. In the past, it was one's "inner life", the world of introspection, of private

Consciousness, at its simplest, is awareness of internal and external existence. In the past, it was one's "inner life", the world of introspection, of private thought, imagination and volition. Today, it often includes any kind of cognition, experience, feeling or perception. It may be awareness, awareness of awareness, or self-awareness either continuously changing or not.