The system database mainly contains the data dictionary tables that stores the object's metadata and system tables for other operational purposes. The system database contains a number of system tables. We will learn more about them in the coming sections.
The system database
Data dictionary tables
The data dictionary tables contains the metadata about data objects. Tables of this directory are invisible and are not read by general SQL queries such as SELECT, SHOW TABLES, INFORMATION_SCHEMA.TABLES, and so on. MySQL mainly exposes the metadata using the INFORMATION_SCHEMA option.