This is the most comprehensive commentary on both Divisions of Heidegger's Being and Time, making it the essential guide for newcomers and specialists alike. Beginning with a non-technical exposition of the question Heidegger poses--What does it mean to be?--and keeping that question in view, it gradually increases the closeness of focus on the text. Citing Joan Stambaugh's translation, the author explains the key notions of the original with the help of concrete illustrations and reference to certain of the most relevant works Heidegger composed both before and after the publication of Being and Time.