  In these notes we introduce briefly the fundamentals of the replica method in
the context of liquid theory and the structural glass problem. In particular,
we explain and show its usefulness as a computation framework in the context of
the Random First Order Transition (RFOT) theory of the glass transition, whose
defining points the reader is assumed to know. We shall give the intuitive idea
of how and why the replica method is suitable for the description of the glass
transition (the dynamical glass transition in particular) in real liquids, and
then show how it can be used to make explicit computations and predictions that
can be compared to experiments and numerical simulations.
