a GIS operation that affixes data from one feature layer’s attribute table to another from a spatial perspective. Spatial joins begin by selecting a target feature and comparing it spatially to other feature layers. There are two types of spatial joins—spatial join by attribute and spatial join by location. Both of them are ways that the mapping software will let you add data from one map layer or file to another map layer. A spatial join by attribute is used when you want to join non-spatial data, such as a text file, to spatial data, such as a shapefile. A spatial join by location is used when you want to join two layers of spatial data (e.g. a points layer to a polygon layer).