live CD

A live CD or live disk is a self-contained bootable and fully operational operating system (OS) on a disk, typically a CD or DVD or even a USB drive, depending on the size of the OS. This version of an OS can boot and run on a PC without ever needing to be installed on the computer's hard drive or changing the PC settings, allowing a user to recover files on a computer with a corrupted OS or to simply experiment on different things without fear of corrupting any files on the disk or the OS installation. Some versions of Linux are small and portable enough to function in a live CD.