This document provides an overview of Geonetwork, an open source software for cataloguing geospatial data. It discusses why Geonetwork is needed, including to catalogue geospatial data, expose metadata in ISO standards, and implement spatial searches. Geonetwork is adopted because it is open source, has an active community and userbase, and allows for easy updates. The document then covers how to deploy and use Geonetwork, loading metadata standards and records, and harvesting from OGC services. Known deployments of Geonetwork around the world are also listed.