This book presents the solution for the data transformation from XML into ontology and the solution for integration of XML data. We propose a hybrid similarity measure based approach, that handles the distinct problems of syntactic, semantic, and schematic heterogeneity of XML data. Our similarity measure addresses both structural and semantic components and can be applied for both schema types, XSD and DTD . Due to the different targets between integration and transformation of XML data, we propose two types of similarity measures, which are similarity of elements between two schemas for data integration and similarity of elements within a schema for data transformation.