C*-Algebras. Normed Involutive Algebras. Positive Forms and Representations. The Spectrum of a C*-Algebra. Liminal C*-Algebras. The Type of a Representation. Traces and Representations. The Quasi-Spectrum. Integration and Disintegration of Representations. C*-Algebras of Type I. Continuous Fields of C*-Algebras. Extension to C*-Algebras of the Stone-Weierstrass Theorem. The Enveloping von Neumann Algebra of a C*-Algebra. Applications to Group Representations. Unitary Representations of Locally Compact Groups. Square-Integrable Irreducible Representations. Representations of Compact Groups. Almost-Periodic Functions. Characters of a Locally-Compact Group. The Dual of a Locally-Compact Group. Appendices. References.