Floppy disks are portable removable disks that use surfaces coated with magnetic oxide materials that can store digital computer data as magnetic charges. The disks are referred to as being 'floppy' because the original 8" disks created by IBM researchers (c. 1971 Alan Shugart and team) tended to bend or 'flop'. Every portable magnetic removable disk therafter tended to be referred to as a 'floppy' disk.
Floppy disks came in a variety of formats and capacities. As the speed and size of computer memory and hard drive storage grew, floppies became less and less useful. Most new PCs no longer ship with a floppy drive, but usually still ship with a floppy drive controller on the mainboard. The original 8 inch disk (~100 KB) was created by IBM, which they followed up with a 5.25 inch disk (~1.2 MB double sided, double-density). Later Sony created a 3.5 format floppy disk (~400KB, 720KB or 1.44MB in high-density) inch disk which is the most common 'floppy' today.
As computer mainboards were designed to allow computers to boot from other types of media, f loppy drives have been eclipsed by CD-ROMs and USB flash memory devices.