  It is by now well established that Dirac fermions coupled to non-Abelian
gauge theories can undergo an Anderson-type localization transition. This
transition affects eigenmodes in the lowest part of the Dirac spectrum, the
ones most relevant to the low-energy physics of these models. Here we review
several aspects of this phenomenon, mostly using the tools of lattice gauge
theory. In particular, we discuss how the transition is related to the
finite-temperature transitions leading to the deconfinement of fermions, as
well as to the restoration of chiral symmetry that is spontaneously broken at
low temperature. Other topics we touch upon are the universality of the
transition, and its connection to topological excitations (instantons) of the
gauge field and the associated fermionic zero modes. While the main focus is on
Quantum Chromodynamics, we also discuss how the localization transition appears
in other related models with different fermionic contents (including the
quenched approximation), gauge groups, and in different space-time dimensions.
Finally we offer some speculations about the physical relevance of the
localization transition in these models.
