Most geotechnical behavior is unseen, under the ground surface. Monitoring, physical and numerical modeling, and the evaluation of performance in hind cast studies are valuable options to measure and understand the behavior of a structure and its subsoil. It is not sufficiently recognized that a geotechnical design based on simple rules will suffer from lack of safety and excessive expenses. Monitoring and physical modeling should be always part of a design framework in order to convince stakeholders and decision makers to care for realistic geotechnical uncertainties. This general report elaborates on the uncertainties our profession has to deal with and describes a framework to determine and explain the various geotechnical uncertainties and a framework to decrease uncertainties by proper understanding of the behavior of geotechnical structures.