This volume is devoted to Quantum Decoherence with lectures from the
Séminaire Poincaré, held in November 2005 at the Institute Henri
Poincaré Paris. The goal of this seminar is to provide up-to-date
information about general topics of great interest in physics. Both the
theoretical and experimental results are covered, with some historical
background. Particular care is devoted to the pedagogical nature of the
presentation.