Floppy disks are small, removable, media storage devices. They record data onto a thin, circular magnetic film encased in a flat, square plastic jacket. This type of media is somewhat antiquated, having been replaced by flash memory and re-writable CD storage devices.
The original floppy disks were 8-inch (20.32 cm) floppies used in 1971-1975, but the first that were widely used commercially were 5.25-inch (13.335-cm) disks. They were quite flexible and required a floppy drive of the same size. The disks could store up to 360 kilobytes (KB) of data, or about one third of a single megabyte. Later, high-density floppies held 1.2 megabytes (MB) of data. These were widely used until about 1987.
As the technology of floppy disks improved, the next generation was smaller and eventually held more data. The newer 3.5-inch (8.89-cm) disks also had hard shell cases for protection, making them less floppy, although the term floppy disk was still used for many years, however. Some only used one side of the internal magnetic film for recording data, giving them a capacity of 744 KB. High-density 3.5-inch floppies doubled the capacity to 1.44 MB. In fact, there were several configurations, including single or double sided (SS or DS), and single or double density (SD or DD).
An easy way to spot the lower capacity diskette was to look at the top corners of the case or jacket. If the diskette had only one hole on the right, it was a single-sided diskette. The hole on the top right of the disk included a small plastic tab, which allowed the user to write-protect the disk.
Since double-density floppy disks were cheaper than their higher-capacity high-density cousins, some people in the know would purchase the cheaper disks, then drill a hole in top left corner to convert the disk to a double-sided high-density disk. All disks contained a polyester film called BoPET — better known as Mylar® — coated on both sides with the necessary magnetic material. Punching a second hole in the case allowed the floppy drive to spin the film in the opposite direction, thereby utilizing both sides.
Various technologies have been used since 1991 in the attempt to extend the life of floppies by increasing their capacity to 2.88 MB (extended density or ED), and even 120 MB and 240 MB (LS-120 and LS-240 respectively). None of these technologies caught on, however. The former proved to be too small an increase of capacity for ubiquitous adoption, and the latter an unreliable form of storage.
Today, other storage devices that are more convenient and robust, such as compact disks and flash memory, have largely replaced floppy disks. A CD can hold upwards up 600 MB, and even the smallest capacity memory stick holds several hundred times the amount of a single floppy. Some memory sticks now compete with smaller hard drives for disk capacity, making them ideal for transferring files, programs, or even entire volumes.
A real sign that floppy disks are all but obsolete is that most laptops no longer come with a floppy drive, and many desktop systems do not include this drive unless requested. Nevertheless, some people continue to use diskettes for backing up and transferring small files.