From Msoft info User Account Control (UAC) is a feature in Windows that can help you stay in control of your computer by informing you when a program makes a change that requires administrator-level permission. UAC works by adjusting the permission level of your user account. If you’re doing tasks that can be done as a standard user, such as reading e‑mail, listening to music, or creating documents, you have the permissions of a standard user—even if you’re logged on as an administrator.
...used with program installation, changing windows firewall settings and such like.