1 GENERALITIES 1 1.1 Why Robust Procedures? 1 1.2 What Should a Robust Procedure Achieve? 5 13 Qualitative Robustness, 7 1.4 Quantitative Robustness, 10 1.5 Infinitesimal Aspects, 13 1.6 Optimal Robustness, 16 1.7 Computation of Robust Estimates, 17 2 THE WEAK TOPOLOGY AND ITS METRIZATION 20