A disk or disk cartridge that is inserted into the drive for reading and writing and removed when not required. Using optical technologies, CDs and DVDs are the most common examples.

Before the Internet and high-speed modems, and before the widespread use of external hard disks that plug in via USB, many types of removable, cartridge-based magnetic disks were introduced for backup use or transportable storage. All such products exceeded the limited capacity of the floppy disk (see magnetic disk). In the 1980s, SyQuest pioneered the removable magnetic disk (see SyQuest). See Zip disk, REV disk and optical disc.