MD Data is a type of magneto-optical medium derived from MiniDisc.
In developing and marketing it, Sony was trying to set the new standard for removable media to replace the 3½-inch diskette it had also helped create. MD Data competed in a format war with other disks such as SyQuest's EZ 135, Imation's SuperDisk, and the Iomega Zip. Ultimately neither MD Data nor any of its competitors succeeded in becoming the de facto new universal standard fully replacing the 3.5 inch diskette; with recordable CDs coming closest to filling the role, followed by USB flash drives.