Quick Info (IntelliSense)
The Microsoft IntelliSense Quick Info option displays the complete declaration for any identifier in your code. When you move the mouse pointer over an identifier, its declaration is displayed in a yellow pop-up window.
In the Database Engine Query Editor, Quick Info is available only for those parts of the Transact-SQL syntax that IntelliSense supports. For example, if you move the mouse pointer over the identifier for an object that has a data type that IntelliSense does not support, the Quick Info pop-up window contains a message that states that the data type is not supported.