What do you know about Windows authentication and Sql server authentication?

When you are connecting to a SQL Server Instance, you are asked to enter user name and password in order to verify that you have access to he SQL Server and/or database.

It is possible to use either Windows account (Domain account) or SQL Server account (login). During the SQL server installation it is possible to configure whether the server will accept SQL Server accounts/logins only or Windows domain accounts only or both (Mixed Mode).