User Account Control (UAC) is a feature in Windows that can help prevent unauthorized changes to your computer. UAC does this by asking you for permission or an administrator password before performing actions that could potentially affect your computer's operation or that change settings that affect other users. When you see a UAC message, read it carefully, and then make sure the name of the action or program that's about to start is one that you intended to start.
By verifying these actions before they start, UAC can help prevent malicious software (malware) and spyware from installing or making changes to your computer without permission.
When your permission or password is needed to complete a task, UAC will alert you with one of the following messages:
A Windows function or program that can affect other users of this computer needs your permission to start. Check the name of the action to ensure that it's a function or program you want to run.
A program that's not part of Windows needs your permission to start. It has a valid digital signature indicating its name and its publisher, which helps to ensure that the program is what it claims to be. Make sure that this is a program that you intended to run.
An unidentified program is one that doesn't have a valid digital signature from its publisher to ensure that the program is what it claims to be. This doesn't necessarily indicate danger, as many older, legitimate programs lack signatures. However, you should use extra caution and only allow this program to run if you obtained it from a trusted source, such as the original CD or a publisher's website.
This is a program that your administrator has specifically blocked from running on your computer. To run this program, you must contact your administrator and ask to have the program unblocked.
We recommend that you log on to your computer with a standard user account most of the time. You can surf the Internet, send e‑mail, and use a word processor, all without an administrator account. When you want to perform an administrative task, such as installing a new program or changing a setting that will affect other users, you don't have to switch to an administrator account. Windows will prompt you for permission or an administrator password before performing the task.
To help protect your computer, you can create standard user accounts for all the users who share the computer. When someone who has a standard account tries to install software, Windows will ask for an administrator account's password so that software can't be installed without your knowledge and permission.