Diagnostic software tools are used to identify problems on a computer or piece of equipment. They test onboard systems to detect issues and alert users of potential problems or breakdowns. Some common downloadable diagnostic tools include programs that protect against malware, repair registry errors, improve system performance and stability, clean the registry, and tune up and maintain PCs with functions like anti-spyware and privacy protection. Disk management tools allow users to format drives, check for physical errors, optimize disk space usage, remove unused files, create partitions, and scan operating system files.