User Account Control (UAC) is a new feature introduced in Windows Vista that helps minimize the dangers of unwanted actions or unintended software installations. UAC prompts for permission before allowing changes that can affect your computer's security or performance. How UAC works depends on the user account type:
- A standard user account is an account that has the least amount of user rights and privileges required to perform most basic tasks. An administrator account can perform any action on the system.
- Regardless of the user account type, the system first attempts to perform any action using standard user privileges. If standard user rights are not sufficient to perform a task, UAC requests privilege elevation:
- The standard user is prompted to provide administrator user credentials (username and password). This process is referred to as Prompt for credentials.
- The administrator user is asked whether the requested task should be allowed. Because the administrator has already logged on with an administrator username and password, this is a simple Continue or Cancel question. This process is referred to as Prompt for consent.
- Prompting for credentials or consent activates the Secure Desktop. With the Secure Desktop, the desktop and all active applications are darkened, and the prompt appears over the shaded desktop. You must respond to the prompt before you can continue with the requested operation or return to the desktop.
- Actions that require elevated credentials are typically indicated in the interface with a shield.
- You can turn off UAC by going to User Accounts in the Control Panel. You must restart the computer to apply the changes.
- You can use the Local Security Policy to customize other ways that UAC works. For example, you can disable the Secure Desktop; the prompt will still be shown, but you will not be locked out of the rest of the desktop while the prompt is waiting for action.