The integrated information theory (IIT) of consciousness attempts to explain consciousness, or conscious experience, at the fundamental level using a principled, theoretical framework. The theory starts from two key postulations regarding the nature of consciousness: That consciousness has information regarding its experience, and that the experience is integrated to the extent that parts of an experience are informative of each other.[1]

Here, IIT embraces the information theoretical sense of information; that is, information is the reduction in uncertainty regarding the state of a variable, and conversely is what increases in specifying a variable with a growing number of possible states. When applied to conscious experience as we know it, since the number of different possible experiences generated by a human consciousness is considerably large, the amount of information this conscious system must hold should also be large. The list of a system's possible states is called its "repertoire" in IIT.