​The relevance of the Unified Soil Classification System (USCS) becomes evident when it is analyzed taking into consideration the particulate nature of soils. Furthermore, a fundamental analysis helps identify important soil parameters that are not adequately considered in routine geotechnical laboratory practice. These parameters include: specific surface and surface charge, particle shape, saturation, small-strain shear stiffness, spatial variability, in-situ void ratio and critical state soil parameters. This manuscript includes a brief discussion of these parameters and a detailed description of simple yet effective procedures that can be used for their quantification.