The paper introduces a new family of description logics (DLs) called *DL-Lite*, designed to capture basic ontology languages while maintaining low complexity in reasoning. The authors demonstrate that for the DLs in the *DL-Lite* family, standard DL reasoning tasks, such as computing subsumption and checking satisfiability, are polynomial in the size of the TBox (axiomatization of concepts and roles). Additionally, query answering over the instance level (ABox) is shown to be LogSPACE in the size of the ABox, marking the first result of polynomial-time data complexity for query answering in DL knowledge bases. Notably, the *DL-Lite* family allows for a separation between TBox and ABox reasoning during query evaluation, enabling efficient use of current database management systems for query optimization. The authors conclude that the *DL-Lite* family is the maximal set of DLs supporting efficient query answering over large amounts of instances, making it suitable for applications like the Semantic Web and data integration.The paper introduces a new family of description logics (DLs) called *DL-Lite*, designed to capture basic ontology languages while maintaining low complexity in reasoning. The authors demonstrate that for the DLs in the *DL-Lite* family, standard DL reasoning tasks, such as computing subsumption and checking satisfiability, are polynomial in the size of the TBox (axiomatization of concepts and roles). Additionally, query answering over the instance level (ABox) is shown to be LogSPACE in the size of the ABox, marking the first result of polynomial-time data complexity for query answering in DL knowledge bases. Notably, the *DL-Lite* family allows for a separation between TBox and ABox reasoning during query evaluation, enabling efficient use of current database management systems for query optimization. The authors conclude that the *DL-Lite* family is the maximal set of DLs supporting efficient query answering over large amounts of instances, making it suitable for applications like the Semantic Web and data integration.