High Level Architecture
The following graphic presents a high level (and highly simplified) view of the ANSI/SPARC architecture.
ANSI/SPARC specifically names three levels of the architecture.
The External level is composed of all the different views (not specifically in the sense of views in relational systems) of the underlying physical database.
The Conceptual level is concerned with transparently mapping External level views to the physical storage of the actual data in the database. In terms of a relational system, this level is composed of the database management system and the file system.
The Internal level describes the physical storage of the data on the storage media.