A geoportal is a Web site providing a single point of access to spatial data, allowing its users to browse through extensive collections of data and related materials, evaluating their potential fitness for use. Geoportals may include data that are in the public domain or available free of charge, and may also support licensing and purchasing of proprietary data. They include the ability to search through catalogues, examining the contents and quality of data. Geoportals include standard layers of data on topography, roads and streets, rivers and streams, named places, imagery, and political boundaries; and may also provide access to more specialised data. A number of geoportals are listed in the Web links: “Selected data and information sources” Annex to this Guide.