Preface .- Introduction .- Hadamard Sets.- $\epsilon$-Kronecker sets.- Sidon sets: Introduction and decomposition properties.- Characterizations of $I_0$ sets.- Proportional characterizations of Sidon sets.- Decompositions of $I_0$ sets.- Sizes of thin sets.- Sets of zero discrete harmonic density.- Related results.-Open problems.- Appendices (Groups, Probability, Combinatoric results, ...).- Bibliography.- Author index.- Subject index.- Index of...