 The most initially plausible and promising way to explain what the entropy of a black hole measures, and why a black hole has such a property in the first place, is to point to the Hawking radiation it emits, and in particular the well defined temperature the radiation has. (For exposition and discussion of the standard relations between temperature and entropy in classical thermodynamics, see, e.g.: Fermi 1936 for a less technical, more physically intuitive approach; Fowler and Guggenheim 1939 for a more technical and rigorous one; and Uffink 2007 for a more historically and philosophically oriented one.) Indeed, it is not uncommon to see such “explanations”, not only in popular accounts but even in serious research papers. There are, however, many technical and conceptual reasons why such an explanation is not viable (Visser 1998b, 2003), summed up in the slogan that Hawking radiation is a strictly kinematical effect, whereas black hole entropy is a dynamical phenomenon. (This fact is discussed in more detail in  section 8  below.) What, then, is the origin and nature of the entropy we attribute to a black hole? 