In computer science, the terms TBox and ABox are used to describe two different types of statements in knowledge bases. TBox statements are the "terminology component", and describe a domain of interest by defining classes and properties as a domain vocabulary. ABox statements are the "assertion component" — facts associated with the TBox's conceptual model or ontologies. Together ABox and TBox statements make up a knowledge base or a knowledge graph. ABox statements must be TBox-compliant: they are assertions that use the vocabulary defined by the TBox.