Due to the chiral symmetry of the QCD Lagrangian (in the limit of massless
light quarks), it is possible to develop a rigorous and systematic
formalism for low energy processes known as Chiral Perturbation Theory
(PT). There has been a great deal of development in this theory and
its consequences over the last few years.
PT establishes
relationships between different physical observables in terms of 10
renormalization constants; interactions with nucleons can also be
calculated in terms of additional parameters. By performing a variety of
different experimental measurements, the renormalization parameters can be
over-determined and the internal consistency of the theory can be tested.
Precise new experimental data have become available that demonstrate the predictive power of this approach in addition to challenging the limits of its applicability. We discuss here the present status and future prospects of the part of this program that is pursued using electromagnetic (i.e., real and virtual photon) interactions.