A DOS utility included only in Windows 95/98/ME that detected and repaired errors on disk. Similar to the Chkdsk utility, ScanDisk reclaimed lost clusters and turned them into .CHK files. It also performed a surface scan of the disk. ScanDisk (SCANDISK.EXE) was first shipped with DOS 6.2 and used a character-based menu interface. If Windows crashed or the computer lost power, the next time the computer was booted, ScanDisk ran automatically.
Chkdsk (CHKDSK.EXE) is a command line program that reclaims lost clusters and has shipped with every version of Windows thus far. See lost cluster