Exclusive hard reactions and QCD

Exclusive reactions at large momentum transfer allow to probe the structure of hadrons, in particular of the pion and nucleon, on the amplitude level. They are challenging both the experimental measurements and the theoretical understanding of Quantum Chromodynamics. We shortly introduce the concept of factorization, emphasize the importance of new experimental nucleon and photon-to-pion form factor measurements, and report on phenomenological progress in the description of hard exclusive electroproduction of photons, providing access to generalized parton distribution.