The point of departure of this book is a triad of themes: information theory, thermodynamics, and quantum mechanics. These are related: thermodynamics and quantum mechanics form the basis of quantum thermodynamics; information and quantum mechanics underly, inter alia, the notorious quantum measurement problem; and information and thermodynamics have much to say about control limits in the tension between micro- and macro-descriptions. Why does the world around us typically look thermal-from cosmology down to individual embedded spins? Do informational measures constitute additional (independent) parameters beyond physical ones? Is the transition between mechanical and thermal systems gradual or discontinuous? Pertinent examples can be found in various processes implemented on small quantum systems. Particularly attractive are model systems that can be treated thermodynamically, but-to some extent-also exactly, that is, based on pure quantum dynamics. This possibility opens the door to nano-thermodynamics. In this sense, the book aims at a modern perspective of nanoscale applications, defined here as a potential realization of various functions as constrained by given resources.