Book excerpt: Introduction to Object-Oriented Databases provides the first unified and coherent presentation of the essential concepts and techniques of object-oriented databases. It consolidates the results of research and development in the semantics and implementation of a full spectrum of database facilities for object-oriented systems, including data model, query, authorization, schema evolution, storage structures, query optimization, transaction management, versions, composite objects, and integration of a programming language and a database system.The book draws on the author's Orion project at MCC, currently the most advanced object-oriented database system, and places this work in a larger context by using relational database systems and other object-oriented systems for comparison.Won Kim is Director of the Object-Oriented and Distributed Systems Laboratory at Microelectronics and Computer Technology Corporation (MCC) in Austin, Texas.Contents: Introduction. Data Model. Basic Interface. Relationships with Non-Object-Oriented Databases. Schema Modification. Model of Queries. Query Language. Authorization. Storage Structures. Query Processing. Transaction Management. Semantic Extensions. Integrating Object-Oriented Programming and Databases. Architecture. Survey of Object-Oriented Database Systems. Directions for Future Research and Development.