We save and open data in a FILE.
But, files have limitations in terms of performance, security, convenience.
DATABASE is a specialized software designed to overcome the limitations that files have.
Examples of database products: MySQL, Oracle, SQL Server, PostgreSQL, MongoDB ...
CORE: how to input and output data from the database
Input: CUD (Create, Update, Delete)
Output: R (Read)
File -> Spreadsheet -> Database
Database Model