  Colloidal model systems allow studying crystallization kinetics under fairly
ideal conditions with rather well characterized pair interactions and minimized
external influences. In complementary approaches therefore experiment, analytic
theory and simulation have been employed to study colloidal solidification in
great detail. These studies were based on advanced optical methods, careful
system characterization and sophisticated numerical methods. Both the effects
of the type, strength and range of the pair-interaction between the colloidal
particles and those of the colloid-specific polydispersity were addressed in a
quantitative way. Key parameters of crystallization were derived and compared
to those of metal systems. These systematic investigations significantly
contributed to an enhanced understanding of the crystallization processes in
general. Further, new fundamental questions have arisen and (partially) been
solved over the last decade including e.g. a two step nucleation mechanism in
homogeneous nucleation, choice of the crystallization pathway or the subtle
interplay of boundary conditions in heterogeneous nucleation. On the other
side, via the application of both gradients and external fields the competition
between different nucleation and growth modes can be controlled and the
resulting micro-structure be influenced. The present review attempts an account
of the interesting developments occurred since the turn of the millennium and
an identification of important novel trends with particular focus on
experimental aspects.
