Consciousness: An Introduction 3rd Edition

Is there a theory that explains the essence of consciousness? Or is consciousness itself just an illusion? The 'last great mystery of science', consciousness is an area of cognitive psychology that was once viewed with extreme scepticism and was consequently avoided by the majority of mainstream scientific researchers. However, it has now become a significant area of research despite the complexity of the subject matter. There is no universally accepted definition of what consciousness entails, although most psychology academics would acknowledge that broadly speaking, it explores the experience of being aware of an external object or something within oneself.