  Notes on holographic renormalization as a tool for UV analysis and derivation
of the two-point Ward identity encoding symmetry breaking. Goldstone theorem is
reviewed, discussing in particular the modifications required by its extension
to non-relativistic field theories. The Ward identity encoding both spontaneous
and explicit breaking are derived by general principles. Holographic
renormalization is presented in a quite operational fashion. The derivation of
the Ward identity in holography is illustrated by an example.
