It can be used to recover data from external and internal hard disks, in FAT, NTFS, HFS and HFS+ file systems.
[2] In the drive recovery technique the program finds orphaned file system entries and reconstructs the missing/lost/corrupted volumes.
The user can help the program by selecting file types that may have existed on the old system, but for majority of cases the automatic detection works.
This is obtained from non-deleted file system records such as from the NTFS $MFT as discussed here.
This computer data storage-related software article is a stub.