User Account Control (UAC) is a security feature in Windows operating systems that helps prevent unauthorized changes to the system. It is an important topic for Windows users as it provides an additional layer of protection against malware and other malicious activities.

UAC works by prompting users for permission or elevation when performing tasks that require administrative privileges. This ensures that only trusted applications and processes can make changes to the system. By default, UAC is enabled in Windows, and it is recommended to keep it enabled for enhanced security.

Examples:
1. Prompting for elevation: When a user tries to install a program or make changes to system settings, UAC prompts for permission or asks the user to enter the administrator password. This prevents unauthorized software installations or modifications.

2. Virtualization: UAC uses a feature called virtualization to redirect write operations from restricted locations to user-specific locations. For example, if a non-administrator user tries to write to the "Program Files" folder, UAC redirects the write operation to a virtualized folder specific to that user, ensuring system integrity.

3. UAC settings: Users can customize UAC settings based on their preferences. This includes adjusting the notification level, which determines how often UAC prompts for permission, and enabling or disabling UAC altogether.