Foundations and Applications of Schema Mappings Phokion G. Kolaitis UC Santa Cruz and IBM Almaden Research Center Schema mappings are high-level specifications that describe the relationship between two database schemas. Schema mappings constitute the essential building blocks in formalizing the main data inter-operability tasks, including data exchange and data integration. The aim of this talk is to present an overview of recent developments in the study of schema mappings with emphasis on their uses in data exchange and on results about operators for managing schema mappings.