Cold Cathode Fluorescent Lamp (CCFL) belong to gas discharge lamp.
There are rare gases and a slight amount of mercury inside the phosphor coated glass tube. Few electrons will hit electrodes when high voltage is given on both ends of electrodes. The more and more electrons come out, as a result of this, gas discharge occurs. Mercury atoms will emit 253.7nm ultraviolet radiation, which give the visible light in the end with the help of tri-phosphor.