A database and all the additional information required for its operation are collectively known as a database instance. Each database instance has a database name and consists of volumes, all the files in the run directory, and a collection of metadata (including configuration data, database parameters, and volume paths).
You can create database instances with the Installation Manager or the Database Manager database tool.
Concepts of the Database System, Overview of the Database System
Database Manager GUI, Creating a Database Instance
Database Manager CLI, db_create