CHKDSK (short for "check disk") is a command on computers running DOS, OS/2 and Microsoft Windows operating systems that displays the file system integrity status of hard disks and floppy disk and can fix logical file system errors. It is similar to the fsck command in Unix.
The command is implemented as an executable program file, CHKDSK.EXE. Different operating systems all use the same filename, but the files are not necessarily compatible between operating systems.
On computers running NT-based versions of Windows, CHKDSK can also check the disk surface for physical errors or bad sectors, a task previously done by SCANDISK. This version of CHKDSK can also handle some physical errors and recover data that is still readable.
Read more about CHKDSK: Windows NT-based CHKDSK