  In this thesis we review the Seiberg-Witten solution of four dimensional N=2
gauge theories, the six-dimensional construction of these models recently
proposed by Gaiotto and the BPS quiver technique for the determination of the
BPS spectrum of N=2 theories. We then study how these recent developments allow
to better understand nonperturbative aspects such as confinement and dynamical
symmetry breaking in the N=1 theories obtained starting from N=2 SQCD and
adding a mass term for the chiral multiplet in the adjoint of the gauge group.
We find an unusual realization of the 't Hooft-Mandelstam mechanism, in which
confinement and dynamical symmetry breaking are due to the condensation of
different degrees of freedom.
