  An overview of the behavior of materials at high pressure is presented,
starting from the effects on single atoms driving electronic transitions and
changes in periodic trends. A range of high-pressure-induced phenomena in the
solid state are then discussed building on the atomic changes, including
bizarre electronic structures, electrides, compounds of noble gases, changes in
elemental miscibility, and strange structural and bonding configurations. In
the final section, the field of high pressure superconductivity is discussed,
as high pressure phases have generated immense study and excitement as some of
their critical superconducting temperatures approach room temperature.
