  Low and high energy properties of the pion are reviewed in the framework of
chiral quark models. Particular emphasis is put on the simplest version of the
SU(2) NJL model as prototype. The role of gauge invariance in this kind of
calculations is stressed. The results are used as initial conditions for
perturbative QCD evolution equations. At leading order the quark model scale is
$\mu_0 \sim 320 {\rm MeV} $ as determined from the pion distribution functions
and the pion distribution amplitudes.
