Introduction -- The genetic alphabet -- The genetic code -- RNA structure -- Proteins and point mutations -- Proteins and recombination -- Regulatory DNA regions and their reorganization in evolution -- Metabolic pathways -- Metabolic networks -- Drosophila segmentation and other gene regulatory networks -- Phenotypic traits, cryptic variation, and human diseases -- The many ways of building the same body -- Neutral spaces -- Evolvability and neutral mutations -- Redundancy of parts or distributed robustness? -- Robustness as an evolved adaptation to mutations -- Robustness as an evolved adapatation to environmental change and noise -- Robustness and fragility: advantages to variation and trade-offs -- Robustness in natural systems and self-organization -- Robustness in man-made systems.