CCFL
A cold cathode is an element used within some nixie tubes, gas discharge lamps, discharge tubes, and vacuum tubes. The term cold cathode refers to the fact that the cathode is not independently heated. In spite of this, the cathode itself may still operate at temperatures as high as if the cathode were heated.
Cold cathode fluorescent lamps (CCFLs) are usually also called cold cathodes. Neon lamps are a very common example of a cold cathode lamp.
Cold cathodes remain popular for LCD backlighting and enthusiast computer case modders.
