Mainly Two modes are the Authentication Modes in SQL Server they are following as :
Windows mode and Mixed Mode : SQL And Windows.
Process of change the Authentication Mode in SQL Server : To change authentication mode in SQL Server click Start > Programs > Microsoft SQL Server > click SQL Enterprise Manager .
When the open the Window of SWL Enterprise Manager it means it start to run from the Microsoft SQL Server program group. Now Select the server then going to Tools menu > select SQL Server Configuration Properties, and choose the Security page.