  I give a relatively broad survey of thermodynamic curvature $R$, one spanning
results in fluids and solids, spin systems, and black hole thermodynamics. $R$
results from the thermodynamic information metric giving thermodynamic
fluctuations. $R$ has a unique status in thermodynamics as being a geometric
invariant, the same for any given thermodynamic state. In fluid and solid
systems, the sign of $R$ indicates the character of microscopic interactions,
repulsive or attractive. $|R|$ gives the average size of organized mesoscopic
fluctuating structures. The broad generality of thermodynamic principles might
lead one to believe the same for black hole thermodynamics. This paper explores
this issue with a systematic tabulation of results in a number of cases.
