Web Feature Service (WFS)
WFS is an Open Geospatial Consortium specification. For more information about the format itself, see http://www.opengeospatial.org/.
WFS allows a client to retrieve geospatial data encoded in Geography Markup Language (GML) from multiple Web Feature Services. GML is built on the standard web language XML.
WFS differs from the popular Web Map Service specification in that WFS returns a subset of the data in valid GML format, not just a graphic image of data.