The need for this handbook is a direct consequence of a very large accumulation of new theoretical and experimental data on nucleur properties. The first five chapters are devoted to the presentation of experimental and theoretical aspects of the following topics: atomic masses of stable and radioactive nuclides; an intuitive way to understand the empirical trends of masses, based on a microscopic theory; Penning traps used as a modern mass spectrometer of high resolving power, accuracy and sensitivity; basic theoretical concepts and experimental techniques used to measure the nucleur shape parameters; new decay modes by hadron and cluster emission; the proton (p), and the beta-delayed particle emissions: neutron (n), 2n, 3n, 4n, p, 2p, 3p, d, t, etc. A series of tables are given in the second part of the handbook: fundamental constants and energy conversion factors; the decay modes of Gauge and Higgs bosons, leptons, quarks, mesons, baryons, and searches for free quarks, monoples, supersymmetries, compositeness, etc; selected alpha particle emitters; recommended data on y-ray and X-ray standards used for detector calibrations; a comprehensive table of all known nuclides (spin, parity, mass excess, half-life, or abundance for stable nuclei, and the main decay modes with the corresponding branching ratios).