Uncompressed error dump file generated by Windows XP/Vista when a program has an error or crashes; contains a "dump" of the program state when the error happened and other relevant system data recorded at the time of the error.

Compressed Heap Dump files are saved as Minidump (.MDMP) files and may be sent to Microsoft as part of an error reporting and bug fixing process.

Windows Error Reporting settings are stored in the Windows Registry at "HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Windows Error Reporting."

Important: You typically should not open HDMP files unless diagnosing a program crash in a controlled software environment.