Part I Algebraic Theory: Cohomology of Profinite Groups -- Some Homological Algebra -- Duality Properties of Profinite Groups -- Free Products of Profinite Groups -- Iwasawa Modules -- Part II Arithmetic Theory: Galois Cohomology -- Cohomology of Local Fields -- Cohomology of Global Fields -- The Absolute Galois Group of a Global Field -- Restricted Ramification -- Iwasawa Theory of Number Fields -- Anabelian Geometry -- Literature -- Index.