  A brief overview of selected topics in the theory and phenomenology of
neutrino oscillations is given. These include: oscillations in vacuum and in
matter; phenomenology of 3-flavour neutrino oscillations and effective
2-flavour approximations; CP and T violation in neutrino oscillations in vacuum
and in matter; matter effects on \nu_\mu \leftrightarrow \nu_\tau oscillations;
parametric resonance in neutrino oscillations inside the earth; oscillations
below and above the MSW resonance; unsettled issues in the theory of neutrino
oscillations.
