A Live CD is a bootable optical disc that contains a complete operating system, allowing users to run it directly from the CD without installing it on their computer's hard drive. This is useful for testing new operating systems, troubleshooting issues, or accessing files on a malfunctioning system. Typically, a Live CD includes a variety of software applications, such as web browsers and file managers, enabling users to perform tasks like browsing the internet or managing files. Popular examples of Live CDs include distributions of Linux like Ubuntu and Fedora, which provide a user-friendly experience.