This book consists of a single essay that speculates on the question what is housing?, and its opposite question, what is not housing? The essay is organised around two distinct discourses around which housing can be framed. The first, which is the dominant discourse, is what I term policy thinking. This is where housing is seen solely in terms of policy formulation and action. The second discourse is private dwelling, which describes housing in terms of a private space used by households. Private dwelling might be seen as a product of policy, but, in actuality, it precedes policy thinking in being the very purpose of policy. Having made this distinction between policy thinking and private dwelling, and so stated in principle what housing is, the subsequent sections of the essay explore the nature of private dwelling in more detail and so substantiate the distinction between the two forms of discourse.