Boot disk is a disk with which a PC can startup or boot from. The commonly seen boot disk is an internal hard disk, which many PCs employ to start up from. Actually, during the boot operation, the OS installed on the HDD is loaded. Majority of computers allow users to boot from other disks too such as DVD-ROMs, CD-ROMs, FireWire hard drives, floppy disks, etc. To work as boot disks, these disks must have an OS installed which is understandable by the PC.
Boot disks are especially used for:
Almost all computers can boot from a HDD have the OS and other software, they would not called boot disks. CD-ROMs are widely seen media but other media like paper tape or magnetic drivers, zip drives and recently USB flash drives can alos be used as boot disks. CD as well as DVD boot disks are normally used to startup a system only when the OS on the internal hard disk fails to load. This can occur when some errors are encountered on the disk or due to the presence of bad data blocks on that disk. By running a disk repair tool from the DVD or CD, one can easily fix the hard disk and restart from it by means of full OS.
In Windows 7, one can create a system repair disk containing the System Recovery Options menu. The menu has special recovery utilities which can help get Windows running and one can find the menu both on Windows installation disk and computer’s hard drive.