SQL SERVER – QUOTED_IDENTIFIER ON/OFF and ANSI_NULL ON/OFF Explanation

http://blog.sqlauthority.com/2007/03/05/sql-server-quoted_identifier-onoff-and-ansi_null-onoff-explanation/

When create or alter SQL object like Stored Procedure, User Defined Function in Query Analyzer, it is created with following SQL commands prefixed and suffixed. What are these – QUOTED_IDENTIFIER ON/OFF and ANSI_NULL ON/OFF?
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_NULLS ON
GO --SQL PROCEDURE, SQL FUNCTIONS, SQL OBJECTGO
SET QUOTED_IDENTIFIER OFF
GO
SET ANSI_NULLS ON
GO

ANSI NULL ON/OFF:
This option specifies the setting for ANSI NULL comparisons. When this is on, any query that compares a value with a null returns a 0. When off, any query that compares a value with a null returns a null value.

QUOTED IDENTIFIER ON/OFF:
This options specifies the setting for usage of double quotation. When this is on, double quotation mark is used as part of the SQL Server identifier (object name). This can be useful in situations in which identifiers are also SQL Server reserved words.