There are several phenomena where the properties of vacancies and self-interstitials in silicon are manifested in straightforward ways. These include the formation of grown-in microdefects, the diffusion of metals (such as Au, Zn), self-diffusion and the installation of vacancy depth profiles in wafers by Rapid Thermal Annealing. Combining features extracted from the analysis of these phenomena, it is possible to define the diffusivities and equilibrium concentrations of the intrinsic point defects. Their diffusivities are remarkably high, and have weak temperature dependence. Their equilibrium concentrations are very low, and have strong temperature dependence.