Which are the two authentication modes in SQL Server 2k ?

There are two authentication modes in SQL Server 2k: 
-     Windows authentication: if user is already authenticated on the windows domain as valid windows user, SQL Server 2k can be requested to trust authentication by the operating system and allow the user assess to SQL Server 2k based on these credentials. You call a connection using windows authentication as a trusted connection.
-   SQL Server authentication: if the user accessing either has not been authenticated on the windows domain or wants to connect using a SQL Server 2k security account the user can request that SQL Server 2k directly authenticate the user based on submission of a username and password.