What is floppy disk?
A soft magnetic disk. Unlike most hard disks, floppy disks (often called floppies or diskettes) are portable, because you can remove them from a disk drive. Disk drives for floppy disks are called floppy drives. Floppy disks are slower to access than hard disks and have less storage capacity, but they are much less expensive. And most importantly, they are portable.
Floppies come in three basic sizes:
8-inch: The first floppy disk design, invented by IBM in the late 1960s and used in the early 1970s as first a read-only format and then as a read-write format. The typical desktop/laptop computer does not use the 8-inch floppy disk.
5-inch: The common size for PCs made before 1987 and the predecessor to the 8-inch floppy disk. This type of floppy is generally capable of storing between 100 KB and 1.2 MB (megabytes) of data. The most common sizes are 360 KB and 1.2 MB.
3-inch: Floppy is something of a misnomer for these disks, as they are encased in a rigid envelope. Despite their small size, microfloppies have a larger storage capacity than their cousins - from 400 KB to 1.4 MB of data. The most common sizes for PCs are 720 KB (double-density) and 1.44 MB (high-density). Macintoshes support disks of 400 KB, 800 KB, and 1.2 MB.