What is the purpose of the UAC box?

Question

What will be an ideal response?

Answer 1

The purposes of the UAC box are: (1) to prevent malicious background tasks from gaining administrative privileges when the administrator is logged on, and (2) to make it easier for an administrator to log in using a less powerful user account for normal desktop activities, but still be able to perform administrative tasks while logged in as a regular user. For example, suppose you're logged on as an administrator with the UAC box turned off and click a malicious link on a web site. Malware can download and install itself without your knowledge and might get admin privileges on the computer. If you're logged on as a standard user and the UAC box is turned off, the malware might still install without your knowledge but with lesser privileges. The UAC box stands as a gatekeeper to malware installing behind your back because someone has to click the UAC box before the installation can proceed.