Hints on the discovery of radioactivity. The exponential law of radioactive decay: series of decays, transient and secular equilibrium, production and decay, branching ratios. Alpha, beta and gamma decays: phenomenological and theoretical aspects. Exotic decays: emission of protons and clusters. Fission. Hints on nuclear models: collective and single particle models. Environmental radioactivity. Artificial radioactivity. Applications towards medicine, archeology, geology, environmental physics. Hints on nuclear astrophysics. Some particular topics are presented with invited talks given by experts of the field.