Regmon is a monitoring tool developed by Sysinternals, designed to track and log changes made to the Windows registry in real-time. It helps users understand which applications or processes are modifying registry keys, providing insights into system behavior and potential issues. By capturing registry activity, Regmon allows users to troubleshoot problems, optimize system performance, and enhance security. The tool displays detailed information about each registry operation, including the process name, the specific registry key affected, and the type of operation performed, making it a valuable resource for system administrators and advanced users.