A Floppy Disk Drive, also called FDD or FD for short, is a computer disk drive that enables a user to save data to removable diskettes. Although 8" disk drives were first made available in 1971, the first real disk drives used were the 5 1/4" floppy disk drives, which were later replaced with the 3 1/2" floppy disk drives.
A 5 1/4" floppy disk was capable of storing between 360 KB and 1.2 MB of data, and the 3 1/2" floppy disk was capable of storing between 360 KB and 1.44 MB of data. For both sizes of floppy disk, the amount of data that could be stored was dependent on whether the disk was single or double sided, and whether the disk was regular or high density.
Above is an example of each of the different floppy drives. As can be seen, the size of the floppy drive and the diskettes they use have decreased over time.