Critical reading means reading with the goal of finding deep understanding of a material, whether it is fiction or nonfiction. It is the act of analyzing and evaluating what you are reading as you make your way through the text or as you reflect back upon your reading.
Critical reading means that a reader applies certain processes, models, questions, and theories that result in enhanced clarity and comprehension. There is more involved, both in effort and understanding, in a critical reading than in a mere "skimming" of the text. What is the difference? If a reader "skims" the text, superficial characteristics and information are as far as the reader goes. A critical reading gets at "deep structure" (if there is such a thing apart from the superficial text!), that is, logical consistency, tone, organization, and a number of other very important sounding terms.