A floppy disk is a removable, rewritable magnetic recording medium comprising a disk-shaped polymer sheet coated with magnetic material on the front and back, encased in a jacket. It is sometimes also referred to as a flexible disk.

In the 1970s, an 8-inch floppy disk (referred to as a diskette at IBM) was first used as an alternative to the punch card used by the IBM3740 data entry system. But it was not until floppy disks began to be used in disk operating systems that file management mechanisms, as typified by the FAT file system, were introduced. The floppy disk was produced in various sizes ranging from the 8-inch type mentioned earlier and the smaller 5.25-inch type with the same structure, to the 3.5-inch model, which became easier to use with the addition of a hard case, a chucking mechanism using a metal hub and a shutter mechanism in the part providing access to the magnetic head. A wide variety of recording formats existed in the past. For this reason, the floppy disk was not suited for data exchange with other models. A 3.5-inch double-sided high-density floppy disk formatted on a Windows environment has a capacity of 1.44MB which is extremely small and slow in comparison to other recording media. However, because all PCs apart from Mac computers support booting from a floppy disk, it continues to be used for starting up old generation operating systems, as repair disks for emergency recovery and as boot disks for installing operating systems, etc. and is hard to relinquish.

When copying a file to a floppy disk on a GUI such as Windows, it may appear as if the process is completed instantly. However, this is due to the delayed write function provided by the operating system. In fact, the floppy disk should not be taken out until the access lamp on the drive goes out after a file operation is completed. It should be handled with care because many drives do not have a media locking mechanism. Products that are not labeled “formatted” must always be formatted before use. Check that the write protect notch is in the “write enabled” position before setting the floppy disk in the drive and format the disk according to procedures prescribed by the operating system.