Check Disk is a built-in utility in Windows operating systems that scans and repairs file system errors on hard drives. It helps ensure that your data is stored correctly and can prevent issues like data loss or corruption. Users can run this tool manually or schedule it to run automatically during system startup. When you run Check Disk, it checks for bad sectors, lost clusters, and directory errors. If it finds any problems, it can attempt to fix them, making your drive more reliable. Regular use of this tool can help maintain the health of your computer's storage.