We describe some of the important physical characteristics of the `pathways',
i.e. dynamical processes, by which molecular, nanoscale and micron-scale
self-assembly occurs. We highlight the fact that there exist features of
self-assembly pathways that are common to a wide range of physical systems,
even though those systems may be different in respect of their microscopic
details. We summarize some existing theoretical descriptions of self-assembly
pathways, and highlight areas -- notably, the description of self-assembly
pathways that occur `far' from equilibrium -- that are likely to become
increasingly important.Comment: To appear in Annual Review of Physical Chemistr