  Black hole thermodynamics emerged from the classical general relativistic
laws of black hole mechanics, summarized by Bardeen-Carter-Hawking, together
with the physical insights by Bekenstein about black hole entropy and the
semi-classical derivation by Hawking of black hole evaporation. The black hole
entropy law inspired the formulation of the holographic principle by 't Hooft
and Susskind, which is famously realized in the gauge/gravity correspondence by
Maldacena, Gubser-Klebanov-Polaykov and Witten within string theory. Moreover,
the microscopic derivation of black hole entropy, pioneered by Strominger-Vafa
within string theory, often serves as a consistency check for putative theories
of quantum gravity. In this book chapter we review these developments over five
decades, starting in the 1960ies.
