"In MatPortal, ontologies are organized in groups and tagged with categories. Typically, groups associate ontologies from the same project or organization for better identification of the provenance. Whereas categories are about subjects/topics and enable to classify ontologies. As of 2016, MatPortal's categories were established in cooperation with FAO AIMS. In 2024, we moved to UNESCO Thesaurus (https://vocabularies.unesco.org). Groups and categories, along with other metadata, can be used on the “Browse” page of MatPortal to filter out the list of ontologies."