UAC User Interface

Windows 7 uses a shield icon to indicate which features of an application require elevated rights. For example, standard users can run Task Manager but they will need administrator credentials if they click the Resource Monitor button. The shield icon serves to warn users before they attempt to access a feature for which they might not have sufficient privileges.

By default, the consent or credential prompt appears on the secure desktop. The secure desktop freezes and darkens the entire desktop except for the UAC prompt, making it very difficult for malware to trick you into providing consent.