  We review the mathematical framework necessary to understand the physical
content of quantum singularities in static spacetimes. We present many examples
of classical singular spacetimes and study their singularities by using wave
packets satisfying Klein-Gordon and Dirac equations. We show that in many cases
the classical singularities are excluded when tested by quantum particles but
unfortunately there are other cases where the singularities remain from the
quantum mechanical point of view. When it is possible we also find, for
spacetimes where quantum mechanics does not exclude the singularities, the
boundary conditions necessary to turn the spatial portion of the wave operator
into self-adjoint and emphasize their importance to the interpretation of
quantum singularities.
