Before a disk can be useful in a computer, the disk must be formatted. Formatting, also called initializing, organizes the storage area on the disk-it magnetically marks the disk with tracks and sectors, each with indicated boundaries, so that the information you store can later be located easily. The process involves erasing all that is on the disk, testing the disk to make sure all of its sectors are reliable, and creating a directory-an internal address system used for locating information later.
Do be aware that it is easy to mistakenly format a disk you didn't mean to, even a hard disk. I mean, you can reformat a disk that already has valuable information on it. Reformatting makes any existing information invisible so your computer doesn't know it's there. Software such as Norton Utilities can often salvage the information on the disk if you accidentally reformat it-but not if you reformat the disk using a different type of formatting. For example, if you stick a high-density floppy disk in a low-density drive, the computer will insist the disk is unreadable, even if that high density disk contains all your inventory information for the past three years. If you go ahead and reformat the disk for low density, the information will be completely and permanently wiped out.
Most hard disks need special software for formatting. You can also buy both floppy disks and hard disks pre-formatted; they cost more, but it may be worth the savings in time.
On the Macintosh, floppy disks can be formatted by just sticking them in the floppy disk drive. If it's unformatted, the computer will ask if you really want to format the disk. If it's really empty, click yes.
On a pc, the computer knows when you put in an unformatted floppy disk, but it won't automatically format the disk. You have to run a DOS program called FORMAT, or use a disk management utility that can do the job.