This document provides an overview of geostatistics and variogram analysis. It discusses how the variogram describes the spatial correlation of a phenomenon through parameters like the nugget effect and range. Experimental variograms are calculated from data and theoretical models like spherical, exponential, and power models are fitted. The variogram can identify different correlation scales through nested models. Components at different scales can be extracted through kriging. As an example, fertility data from France is analyzed to filter its large-scale spatial structure.