Cold Cathode Fluorescents:
They use high voltage across the tube like a Neon tube works.
They chop the 12v in to a high frequency ac voltage and feed it to a
transformer. The secondary of the transformer is feed to the florescent tube. There light output is a little less than a normal fluorescent light and the power to Run them is also a little less. The only drawback is that they radiate RF noise that can interfere with radio, TV and other RF equipment like your car door clicker. The compact fluorescent lights work on the same principle except for 110 vac and they also put out RF interference. They take the 110 v ac and chop it up to a higher frequency to keep the transformers small so it can be mounted in the base of the bulb.