Available with Geostatistical Analyst license.
An ArcMap geostatistical layer comprises a reference to the data stored on disk, the symbology used to display the layer, and a variety of other information relevant to the layer.
Your ArcMap session can be saved as a map document (.mxd). This saves each layer in the table of contents and their accompanying definitions. You can also save your geostatistical layer as a layer file (.lyr), which will preserve the symbology and can be added to a different ArcMap session. The layer file does not make a copy of the source data but only references it.
To make a geostatistical layer persistent—basically, create a permanent copy of the data on disk (excluding the layer definition)—you can export the contents to either raster or vector format (see Exporting geostatistical layers to a raster format and Exporting geostatistical layers to a vector format). Also refer to Fundamentals of creating a raster from a geostatistical layer for information on how block interpolation is used to generate values for each cell in the raster.