This conceptual overview introduces and explains the concept of geodatabases-object-oriented data models-which are introduced in ArcInfo 8, the world's most advanced Geographic Information System (GIS) software package. Included are explanations of what models are and how they represent reality, how GIS data is structured in digital form, extending the power of databases, and making models of everything from streams to electrical power grids. Users will be able to make their datasets "smarter" by defining the relationships between them and endowing them with specific behaviors. These new characteristics are explained and highlighted with hundreds of map illustrations and diagrams.