In a system composed of connected "mechanisms" (nodes containing information and causally influencing other nodes), the information among them is said to be integrated if and to the extent that there is a greater amount of information in the repertoire of a whole system regarding its previous state than there is in the sum of the all the mechanisms considered individually. In this way, integrated information does not increase by simply adding more mechanisms to a system if the mechanisms are independent of each other. Applied to consciousness, parts of an experience (qualia) such as color and shape are not experienced separately for the reason that they are integrated, unified in a single, whole experience; applied in another way, our digestive system is not considered part of our consciousness because the information generated in the body is not intrinsically integrated with the brain.

In IIT 3.0, the 2014 revision of IIT, five axioms were established in underpinning the theory:[3] Consciousness exists

Consciousness is compositional (structured)

Consciousness is informative

Consciousness is integrated

Consciousness is exclusive