Integrated information theory (IIT) takes as its starting point phenomenology, rather than behavioral, functional, or neural correlates of consciousness. The theory characterizes the essential properties of phenomenal existence—which is immediate and indubitable. These are translated into physical properties, expressed operationally as cause-effect power, which must be satisfied by the neural substrate of consciousness. On this basis, the theory can account for clinical and experimental data about the presence and absence of consciousness. Current work aims at accounting for specific qualities of different experiences, such as spatial extendedness and the flow of time. Several implications of IIT have ethical relevance. One is that functional equivalence does not imply phenomenal equivalence—computers may one day be able to do everything we do, but they will not experience anything. Another is that we do have free will in the fundamental, metaphysical sense—we have true alternatives and we, not our neurons, are the true cause of our willed actions.