The classic removable storage medium of the PC era, floppy disks evolved from 8-inch (IBM, 1971) to 5.25-inch (late 1970s) and the ubiquitous 3.5-inch format (Sony, early 1980s). Common capacities include 360 KB / 1.2 MB (5.25″) and 720 KB / 1.44 MB / 2.88 MB (3.5″), with DD/HD/ED formulations, write-protect notches, and the familiar metal-shutter shell on 3.5″ disks. Used for operating systems, software installs, save files, and data transfer, floppies defined everyday computing from the late 70s through the 90s.
