Like rasters, occasionally you only need vector data to cover a certain area of study (area of interest). Also, like rasters, you can use a layer defining the extent that you want to select only for a portion of a vector layer to make a new layer. The tool that is used for this job is Clip; that is, 'Cookie Cutter' because of how the results look afterwards.
For the example in this recipe, we will use geology.shp
and clip it to the extent of Wake County using census_wake2000.shp
. Any vector layer with the aggregation of polygons covering all of the county will work.