Long baseline neutrino oscillations: Theoretical aspects

We discuss the measurement of the neutrino oscillation parameters at future long baseline experiments in terms of the motivation of the experiments, the quantities of interest from the theoretical point of view, the phenomenology of these experiments, and the experiment choice. We illustrate the oscillation physics potential of a neutrino factory, as a representative for the most challenging technologies. Finally, we point out that a future neutrino oscillation facility might also be affected by the unexpected.