In general, all users must authenticate—unless Auto Login is enabled for a specific user. In this case, a particular user will be logged in automatically when the system starts. This can save some time, especially if a computer is used by a single person. It may impact account security.
If your computer is running in a network environment and you are not the only person using the machine, you are usually prompted to enter your user name and password when you start the system.
Figure 1.1: Default GNOME Login Screen
Procedure 1.1: Normal Login
If your user name is listed, click it.
If your user name is not listed, click Not listed?. Then enter your user name and click Next.
Enter your password and click Sign in.