  First, the relation between black holes and limitations on information of
other systems is developed. After reviewing the relation of entropy to
information, we derive the entropy bound, review its applications to cosmology
and its extensions to higher dimensions, and discuss why black holes behave as
1-D objects when emitting entropy. We also discuss fundamental limitations on
the information of pulses in curved space, and on the rate of disposal of
information into a black hole. We then move on to a discussion of quantum black
holes motivated by the adiabatic invariance of horizon area of classical holes.
We develop an algebraic formalism based on symmetry which gives information on
the area (or mass) spectrum of quantum black holes, and on the degeneracy of
the levels. This last turns out to be consistent with the horizon area-black
hole entropy proportionality while leaving room for corrections.
