Debian live, one of many kinds

so what is a linux live CD???

A Debian Live system is a Debian operating system that does not require a classical installer to use it. It comes on various media, including CD-ROM, USB sticks, or via netboot. Why Debian Live?
Although the Debian Live project is about the framework to create your own customized Live system, we offer some prebuilt images. Currently, builds for three desktop environments (GNOME, KDE and Xfce) as well as the standard system are available.