  I present a unifying scheme for hadronic functions that comprises logarithmic
corrections due to gluon emission in perturbative QCD, as well as power-behaved
corrections of nonperturbative origin. The latter are derived by demanding that
perturbatively resummed partonic observables should be analytic in the whole
$Q^2$-plane if they are to be related to physical observables measured in
experiments. I also show phenomenological consequences of this approach. The
focus is on the electromagnetic pion form factor to illustrate both effects,
Sudakov logarithms and power corrections in leading order of
$\Lambda_{\rm{QCD}}^2/Q^2$. The same approach applied to the inclusive
Drell-Yan cross section enables us to perform an absolutely normalized
calculation of the leading power correction in $b^2\Lambda_{\rm{QCD}}^2$ (b
being the impact parameter), which after exponentiation, gives rise to a
nonperturbative Sudakov-type contribution that provides enhancement rather than
suppression, hence partly counteracting the perturbative Sudakov suppression.
