What is a CD?
A CD (Compact Disk) is a small disk where data can be stored. To use a CD, you need a CD drive physically installed in your PC. CD's can only store a small amount of data (less than a gigabyte). Although they were commonly used in the past, CDs are rarely used nowadays, as the same amount of data can be more easily be transferred with USB sticks or even through the Internet.
Caddy
Unlike floppy disks, CDs were inserted in CD drives directly. While they were not in use, they were placed inside caddies to protect their surface, which, if damaged, would make their data unreadable.
