A Microsoft Windows Emergency Repair Disk (ERD) is a specially formatted diskette that creates backups of important system files and settings and is used to troubleshoot and repair problems in Microsoft Windows NT and Windows 2000 systems.
The Emergency Repair Disk provides only the ability to restore the system to a bootable state.
[1] Note: The emergency repair disk is not to be confused with a standard boot diskette as it cannot be used alone.
From there, choosing the option to repair the system will prompt the user for the ERD.
It can be used for the following repair functions: Microsoft Windows operating system (OS) installation disks (beginning with Windows 2000) include the Recovery Console, which allows the user to perform administrative operations on services, drives, and local data.