A floppy disk, diskette, or floppy diskette (casually known as a floppy or a disk) is a type of disk storage made from a thin, flexible disk coated with a magnetic storage medium. It is enclosed in a square or nearly square plastic shell lined with fabric to help remove dust from the spinning disk. Floppy disks store digital data, which can be read or written when inserted into a floppy disk drive (FDD) connected to or built into a computer or other device. The three most popular formats of floppy disks (and their drives) are the 8-inch, 5¼-inch, and 3½-inch versions.
The first floppy disks, invented and made by IBM in 1971, had a disk diameter of 8 inches (203.2 mm). Subsequently, the 5¼-inch (130 mm) and then the 3½-inch (90 mm) became a ubiquitous form of data storage and transfer into the first years of the 21st century. By the end of the 1980s, 5¼-inch disks had been superseded by 3½-inch disks. During this time, PCs frequently came equipped with drives of both sizes. By the mid-1990s, 5¼-inch drives had virtually disappeared, as the 3½-inch disk became the predominant floppy disk. The advantages of the 3½-inch disk were its higher capacity, its smaller physical size, and its rigid case which provided better protection from dirt and other environmental risks.