Resource Monitor is a built-in tool in the Windows operating system that helps users track the performance of their computer's hardware and software. It provides real-time information about CPU, memory, disk, and network usage, allowing users to see which applications are consuming resources and how efficiently the system is running. By using Resource Monitor, users can identify performance bottlenecks and troubleshoot issues more effectively. The tool offers detailed graphs and statistics, making it easier to understand how resources are allocated and utilized, ultimately helping to optimize system performance and improve overall user experience.