  Theoretical and experimental work concerned with dynamic fluctuations has
developed into a very active and fascinating subfield of mesoscopic physics. We
present a review of this development focusing on shot noise in small electric
conductors. Shot noise is a consequence of the quantization of charge. It can
be used to obtain information on a system which is not available through
conductance measurements. In particular, shot noise experiments can determine
the charge and statistics of the quasiparticles relevant for transport, and
reveal information on the potential profile and internal energy scales of
mesoscopic systems. Shot noise is generally more sensitive to the effects of
electron-electron interactions than the average conductance. We present a
discussion based on the conceptually transparent scattering approach and on the
classical Langevin and Boltzmann-Langevin methods; in addition a discussion of
results which cannot be obtained by these methods is provided. We conclude the
review by pointing out a number of unsolved problems and an outlook on the
likely future development of the field.
