  In these lectures, we shall present some remarkable results that have been
obtained for systems far from equilibrium during the last two decades. We shall
put a special emphasis on the concept of large deviation functions that provide
us with a unified description of many physical situations. These functions are
expected to play, for systems far from equilibrium, a role akin to that of the
thermodynamic potentials. These concepts will be illustrated by exact solutions
of the Asymmetric Exclusion Process, a paradigm for non-equilibrium statistical
physics.
