Introduction -- Compact groups : the work of Weyl -- Unitary representations of locally compact groups -- Parabolic induction, principal series representations, and their characters -- Representations of the Lie algebra -- The plancherel formula: character form -- Invariant eigendistributions -- Harmonic analysis of the Schwartz space -- Appendix 1: Functional analysis -- Appendix 2: Topological groups -- Appendix 3: Lie groups and lie algebras