  Recent developments in the study of primordial black holes (PBHs) will be
reviewed, with particular emphasis on their formation and evaporation. PBHs
could provide a unique probe of the early Universe, gravitational collapse,
high energy physics and quantum gravity. Indeed their study may place
interesting constraints on the physics relevant to these areas even if they
never formed. In the "early Universe" context, particularly useful constraints
can be placed on inflationary scenarios, especially if evaporating PBHs leave
stable Planck-mass relicts. In the "gravitational collapse" context, the
existence of PBHs could provide a unique test of the sort of critical phenomena
discovered in recent numerical calculations. In the "high energy physics"
context, information may come from gamma-ray bursts (if a subset of these are
generated by PBH explosions) or from cosmic rays (if some of these derive from
evaporating PBHs). In the "quantum gravity" context, the formation and
evaporation of small black holes could lead to observable signatures in cosmic
ray events and accelerator experiments, providing there are extra dimensions
and providing the quantum gravity scale is around a TeV.
