Hadrons at finite temperature

We review the basic concepts and tools to study hadronic properties in the medium. Beginning with a discussion of spontaneous breaking of chiral symmetry of QCD in vacuum and its possible restoration at high temperature/density, we introduce current correlation functions and outline methods of constraining them through sum rules. This is followed by a discussion on the evaluation of the vector meson self-energy using effective Lagrangians in the framework of thermal field theory.