In SQL Server Management Studio what is SQLCMD mode?

Question

In SQL Server Management Studio I would like to know what is SQLCMD mode?

Answer 1

"You use SQLCMD scripts when you have to process Windows System commands and Transact-SQL statements in the same script."

"By default, SQLCMD mode is not enabled in the Query Editor. You can enable scripting mode by clicking the SQLCMD Mode icon in the toolbar or by selecting SQLCMD Mode from the Query menu."

Reference: MSDN