Geographic information is collected to support scientific investigations and decision making in a wide variety of domains (e.g., ecology, environmental engineering and science, geography, geosciences, public health, and social sciences). Spatial interpolation, one of the most widely used spatial analysis methods, is often integrated within geographic information systems (GIS) to estimate unknown or unavailable information associated with locations of interest based on collected information. Spatial interpolation is described in most of the textbooks in GIS and spatial analysis. This entry provides a concise but comprehensive review of spatial interpolation methods with a focus on the computation of spatial interpolation.