  In the first part of these lectures, I consider chiral perturbation theory in
the presence of matter fields. It allows to systematically work out the
consequences of the broken chiral symmetry of QCD. As examples, threshold pion
photo- and electroproduction and (spin-flip) nucleon Compton scattering are
considered. The second part deals with the quark structure of the nucleon at
low energies. The various electromagnetic and weak form factors are discussed.
It is shown how parity-violating electron and (anti)neutrino scattering off
nucleons and nuclei can be used as a tool to pin down strange matrix elements
of the proton. The calculation of QED, QCD and heavy quark corrections to these
processes is also touched upon. (Lectures given at the XXXII. Internationale
Universit{\"a}tswochen f{\"u}r Kern- und Teilchenphysik, Schladming, Austria,
February 24- March 5, 1993).
