Databases are designed, built, and populated with data for a specific purpose and for an intended group of users. Databases are built for many different users, including banks, hospitals, high schools, government agencies, and manufacturing companies. The data contained in databases vary and can include account, patient, student, employee, planning, or product data. Users of a database can add new records, insert or change data in existing records, retrieve data from existing records, or delete records from the database.

Databases are designed, built, maintained, and queried using a set of tools called a database management system (DBMS). Often, the DBMS is considered the user interface to the database system because everything else is invisible to the user. The DBMS defines the data in a database using the Data Definition Language (DDL) and handles requests to retrieve, update, or delete existing data or add new...