Geographic data, which can be defined as any data with a geographic component, is often produced by one individual or organization, and may address the needs of various users, including information system analysts, programme planners, developers of geographic information or policy makers. Proper standard documentation on geographic data enable different users to better evaluate the appropriateness of data to be used for data production, storage, update.

The metadata standards supported by GeoNetwork opensource are the ISO 19115:2003 - approved by the international community in April 2003 as a tool to define metadata in the field of geographic information - and the FGDC - the metadata standard adopted in the United States by the Federal Geographic Data Committee. In addition, GNos supports also the international standard Dublin Core for the description of general documents.

This ISO Standard precisely defines how geographic information and related services should be described, providing mandatory and conditional metadata sections, metadata entities and metadata elements. This standard applies to data series, independent datasets, individual geographic features and feature properties. Despite ISO 19115:2003 was designed for digital data, its principles can be extended to many other forms of geographic data such as maps, charts, and textual documents as well as non-geographic data.

The underlying format of an ISO19115:2003 compliant metadata is XML. GeoNetwork uses the ISO Technical Specification 19139 Geographic information - Metadata - XML schema implementation for the encoding of this XML.