A database catalog of a database instance consists of metadata in which definitions of database objects such as base tables, views (virtual tables), synonyms, value ranges, indexes, users, and user groups are stored.
[1][2] It is an architecture product that documents the database's content and data quality.
[3] The SQL standard specifies a uniform means to access the catalog, called the INFORMATION_SCHEMA, but not all databases follow this, even if they implement other aspects of the SQL standard.
For an example of database-specific metadata access methods, see Oracle metadata.
This database-related article is a stub.