Theory of strong interactions of elementary particles in the GeV region.- Recent high energy electron investigations at Stanford University.- Review of nucleon form factors.- Special models and predictions for pion photoproduction (low energies).- Special models and predictions for photoproduction above 1 GeV.- Photoproduction of mesons in the GeV range.- Theoretical aspects of colliding beam experiments.- Experimental techniques.- The use of bubble chambers and spark chambers at electron accelerators.