  In these lectures I want to discuss how the structure functions in deep
inelastic scattering relate to quark and gluon correlation functions. In
particular we will consider the issue of intrinsic transverse momenta of
quarks, which becomes important in processes like 1-particle inclusive
leptoproduction. Some examples of cross sections and asymmetries, in particular
in polarized scattering processes are discussed. We also discuss the operator
structure for azimuthal asymmetries and their evolution.
