WIN.COM is the executable file used to load versions of Windows that run from DOS.
In Windows 3.11 and its predecessors, it is executed either manually from the DOS prompt or as a line in AUTOEXEC.BAT.
In Windows 95 and onward it is automatically invoked by IO.SYS after AUTOEXEC.BAT is processed.
WIN.COM has several parameters that facilitate system recovery and diagnostics.
Corruption of WIN.COM would cause the system to be unable to load the graphical user interface.