The Semantic Web is a project devised by Tim Berners Lee and James Hendler (et al), and adopted by the W3C (the manager of the Internet). The Semantic Web implements ontologies so that machines connected to the Web “understand” each other by sharing common meaning of data using a set of standards. The standards developed by the W3C define among others, an ontology modeling language (OWL) and a query language (SPARQL).
Timbr implements the principles of the Semantic Web in standard SQL, meaning that both the ontology modeling and the queries are done in SQL.