A high-density disk is defined as a high-quality floppy disk capable of holding more data than a double-density disk. High-density disks are 3.5-inch disks that can store up to 1.44MB of data. By comparison, a double-density 3.5 inch disk can hold 720K (or 0.72MB) of data.

High-density disks are the latest in the technical evolution of information storage disks, which began with 5.25-inch disks. These were followed by the smaller, 3.5 inch, single-density disks, which are now obsolete. The double-density disk preceded the high-density disk

Hard drives are also capable of high-density storage. In 1999, the IBM Corporation announced the creation of a prototype high-density disk capable of storing in excess of 20 billion bits of data per square inch of disk. This represents a storage capacity that is three times that of current high-density disk drives. Applications include high-quality audio, video and graphics.