Simple Knowledge Organization System - about standard knowledge organization for the web and semantic web, porting thesauri, classification schemes, taxonomies, glossaries, vocabularies, controlled vocabularies, terminology, terminologies, subject schemes, subject heading schemes, subject indexing, subject indexes, folksonomies, to the semantic web, semantically rich metadata, describing concepts, conceptual information, concept maps, semantic mapping, Knowledge Organization Systems, KOS, for the world wide web, using RDF the Resource Description Framework, complementing OWL the Web Ontology Language, integrating with XML Extensible Markup Language.