What is T-SQL ?

Transact-SQL is a language containing the commands that are used to administer instances of SQL Server; to create and manage all objects in an instance of SQL Server; and to insert, retrieve, modify, and delete data in SQL Server tables. Transact-SQL is an extension of the language defined in the SQL standards published by the International Organization for Standardization (ISO) and the American National Standards Institute (ANSI).
A Transact-SQL statement is a set of code that performs some action on database objects or on data in a database. SQL Server supports three types of Transact-SQL statements: DDL, DCL, and DML.
A DDL statement supports the definition or declaration of database objects such as databases, tables, and views. Three DDL commands: create, alter and drop.
Data control language is used to control permissions on database objects. The DCL commands are grant and revoke.
Data manipulation language is used to select, insert, update, and delete data in the objects defined with DDL