User Account Control (UAC) is a security feature in Microsoft Windows that helps prevent unauthorized changes to the operating system. It prompts users for permission or an administrator password before allowing actions that could affect system settings or install software. This helps protect the computer from malware and unintentional changes. When UAC is enabled, users see a notification when a program tries to make changes that require higher privileges. This ensures that users are aware of potentially harmful actions and can decide whether to proceed. UAC aims to enhance security while allowing users to maintain control over their systems.