A live CD (also live DVD, live disc, or live operating system) is a complete bootable computer installation including operating system which runs directly from a CD-ROM or similar storage device into a computer's memory, rather than loading from a hard disk drive. A live CD allows users to run an operating system for any purpose without installing it or making any changes to the computer's configuration. Live CDs can run on a computer without secondary storage, such as a hard disk drive, or with a corrupted hard disk drive or file system, allowing data recovery.
As CD and DVD drives have been steadily phased-out, live CDs have become less popular, being replaced by live USBs, which are equivalent systems written onto USB flash drives, which have the added benefit of having writeable storage. The functionality of a live CD is also available with an external hard disk drive connected by USB. Many live CDs offer the option of persistence by writing files to a hard drive or USB flash drive.
Many Linux distributions make ISO images available for burning to CD or DVD. While open source operating systems can be used for free, some commercial software, such as Windows To Go requires a license to use. Many live CDs are used for data recovery, computer forensics, disk imaging, system recovery and malware removal. The Tails operating system is aimed at preserving privacy and anonymity of its users, allowing them to work with sensitive documents without leaving a record on a computer's hard drive.[1][2]