The document discusses data definition language (DDL) and data manipulation language (DML) commands. It defines DDL as commands used to define the database structure, including create, drop, alter, and truncate. It defines DML commands as those used to manage data in the database, including select, insert, update, and delete. The document provides examples of each command's syntax and usage. It concludes by summarizing the differences between DDL and DML in terms of usage and how each affects the database.