From the perspective of black hole physics, the present research
examines the thermodynamic geometries of extremal and non-extremal black
hole configurations in string theory and M-theory with 2, 3, 4, 5 and 6
charges. We analyzed the structure of state-space geometry, such as
regularity, existence of critical points, lines, surfaces, hypersurfaces
and associated phase transitions for BPS black holes, rotating black
holes, black strings, black rings, multi-centered black branes, brane
fractionation, Mathur's fuzzballs, subensemble theory in string theory
and bubbling black brane foam solutions in M-theory. Generically, we
find that charged, anticharged and rotating black holes correspond to a
weakly interacting equilibrium statistical basis over Gaussian
fluctuations. The state-space and chemical fluctuations pertaining to
the two parameter giants and superstars can be characterized as an
ensemble of arbitrary liquid droplets or irregular shaped fuzzballs. The
higher derivative corrections are examined due to generalized
uncertainty principle and string theory. Finally, we consider the
unified role of the real Riemannian geometry, ensemble theory, vacuum
fluctuations and D-branes.