$Floppy disk 
A portable storage device that stores information on a thin, flexible disk. The disk is coated with a magnetic material. The information is stored on the disk as a series of magnetic signals using a disk drive. The flexible disk is protected from grubby fingers in a rigid plastic case with a sliding window on one side to allow the disk drive access to the surface of the disk. There are two standard sizes of floppy disk: the larger 5.25in disk can store 1.2Mb of data and is now pretty much obsolete. The more robust and smaller 3.5in disk can store 1.44Mb of data and disk drives of this size are fitted to almost every new PC.