Topological Aspects of Quantum Chromodynamics
  Absolute confinement of its color charges is a natural property of gauge theories such as quantum chromodynamics. On the one hand, it can be attributed to the existence of color-magnetic monopoles, a topological feature of the theory, but one can also maintain that all non-Abelian gauge theories confine. It is illustrated how ``confinement'' works in the SU(2) sector of the Standard Model, and why for example the electron and its neutrino can be viewed as SU(2)-hadronic bound states rather than a gauge doublet.   The mechanism called `Abelian projection' then puts the Abelian sector of any gauge theory on a separate footing. 
Gerard 't Hooft