  Inhomogeneities in deposition may lead to formation of rough surfaces, whose
height fluctuations can be probed directly by scanning microscopy, or
indirectly by scattering. Analytical or numerical treatments of simple growth
models suggest that, quite generally, the height fluctuations have a
self-similar character. The roughness and dynamic exponents are expected to be
universal; depending only on the underlying mechanism that generates
self-similar roughness. Despite its ubiquitous occurrence in theory and
simulations, experimental confirmations of dynamic scaling have been rare. I
shall briefly review the theoretical foundations of dynamic scaling, and
suggest possible reasons for discrepancies with experimental results.
