In computer hardware, a caddy is a container used to protect an optical media disc from damage when handling.
[1] As a cost-saving measure, newer versions use hard-coating technology to prevent scratches and do not need a caddy.
Caddies may be an integral part of the medium, as in some DVD-RAM discs, or separately attached.
[2] Some early CD-ROM drives used a mechanism where CDs had to be inserted into special cartridges, somewhat similar in appearance to a jewel case.
The MiniDisc is a similar concept again, using a small proprietary Magneto-optical type disc instead, also in a fixed unopenable caddy.