Entropy is a buzzword that is used by all kinds of communities, covering biologists, economists, social scientists and even writers. One may speculate that the term “Entropy” acts to provide their profoundness of thinking an appropriate scientific aura. One of the reasons for the bewilderment of the term Entropy is the unheralded appearance is the superabundance of situations bearing this expression. Being so, using the term thus requires that one does respect its precise meaning without effusing unnecessarily its wild growth, adding only to confusion rather than to clarity.

Here I will discuss more precisely its physical role of various notions for entropy. In particular, I will address the proper choice of entropy as it depends on the interests of the individual, the particular situations under study (classical or quantum regime), the degree of precision available and the type and method of description. I further will address the notion of entropy for systems of finite size and those situations of relevance in nanoscience, i.e. when the system under study is strongly interacting with its environment. Finally, I hope to address those intriguing (in parts highly controversial) subtleties occurring for the notions of *work* and *heat* in the deep quantum regime.

Relevant sources are:

[1] S. Hilbert, P. Hänggi, and J. Dunkel, Thermodynamic Laws in Isolated Systems, Phys. Rev. E 90, 062116 (2014).

[2] P. Hänggi, S. Hilbert, and J. Dunkel, Meaning of temperature in different thermostatistical ensembles, Phil. Trans. Roy. Soc. A 374, 20150039 (2016).

[3] P. Talkner and P. Hänggi, Open system trajectories specify fluctuating work but not heat, Phys. Rev. E 94, 022143 (2016).

[4] P. Talkner and P. Hänggi, Aspects of quantum work, Phys. Rev. E 93, 022131 (2016).

Peter Hänggi is known for a series of original and pioneering contributions in the area of statistical physics and driven quantum mechanics.  After his education at the University of Basel, (Ph.D Jan. 1977), and postdoc years at the Universities of Stuttgart, Germany, University of California, San Diego, USA, he was employed assistant professor and promoted to associated professor at the Polytechnic Institute of New York. In 1984 he obtained a call for full professor at an age of 34 at the University of Augsburg, where he built up a whole new physics department. Peter’s research is known worldwide for his seminal contributions to reaction rate theory, various novel phenomena in stochastic processes far from equilibrium, time-dependent driven quantum mechanics, quantum dissipation, quantum thermodynamics and, as well, for relativistic-Brownian motion and -thermodynamics. Among his best known achievements are the description of the phenomenon of Stochastic Resonance, his discovery of coherent destruction of tunneling and his initiation of the field of Brownian motors. Among his many international awards are the Lindhard lectureship prize, Lars Onsager medal, Blaise Pascal medal, M. von Smoluchowski-E. Warburg prize, etc.. He also has been awarded with 9 doctors honoris causa and 2 honorary professorships. His bibliographic data are: WOS h = 90 (# > 43000); Google scholar h = 102 (# > 57000).