When users attempt to log in to a device or to access system resources, Windows uses the process of authentication to verify that the users are who they say they are. Authentication occurs when users enter a username and password to access a user account. Windows OSs use Single-Sign On (SSO) authentication, which allows users to log in once to access all system features versus requiring them to log in each time they need to access an individual resource.

User accounts allow multiple users to share a single computer, with each user having their own files and settings. Windows 7 and Windows Vista have three types of user accounts: Administrator, Standard, and Guest. Each account type provides a user with a different level of control over system resources.

An account with administrator privileges must be created when Windows 7 is installed, as shown in the figure. A user with administrator privileges can make changes that impact all users of the computer, such as altering security settings or installing software for all users. Accounts with administrator privileges should be used only to manage a computer and not for regular use, because drastic changes that affect everyone can be made when using the administrator account. Attackers also seek out an administrator account because it is so powerful. For this reason, it is recommended that a standard user account is created for regular use.

Standard user accounts can be created at any time. A standard user account has fewer permissions than an administrator account. For example, users might have the right to only read, but not modify, a file.

Individuals without a standard user account on the computer can use a guest account. A guest account has limited permissions and must be turned on by an administrator.

To create or remove a user account in Windows 7 and Windows Vista, use the following path:

Start > Control Panel > User Accounts > Add or remove user accounts

Windows XP features a fourth group of users called Power Users. Power Users have privileges that are extended beyond those of standard users, providing them with some of the capabilities given to Administrator accounts. Power users are not able to fully administrate system resources. The group has not been included in Windows 7 or Windows Vista.

To create or remove a user account in Windows XP, use the following path:

Start > Control Panel > User Accounts > Select the Users tab and click Add