An ordinary, or incandescent, light bulb produces light by heating a coiled metal (tungsten) filament until it glows. Incandescent bulbs are inexpensive to produce. Energy-saver, or fluorescent, light bulbs are filled with mercury vapor which is excited to the plasma state using electricity. Though more expensive to purchase, fluorescent blubs last longer, give off less heat and require less energy for the same amount of light output.
Compact Fluorescents lamps or bulbs (CFL).have a small integral ballast made up of electronic components such as Rectifiers (Diodes) Coils (Inductors), Storage Capacitor and an Integrated Circuits (IC). The electronic circuit thus produced is used to rectify or change AC (Alternating Current) to DC (Direct Current) and Voltage Regulator or Booster to produce the high voltage required to ionize the gas inside the bulb. The ionized or high energy particles then hit the mercury deposited inside bulb promoting the electrons into a higher orbit. As the electrons fall back to a lower orbit characteristic white light is produced.
As you can imagine producing the electronic circuit adds substantial cost to manufacturing the bulb. Over time the storage capacitors degrade and the bulb begins to produce pinkish light. Sometimes the circuit may fail prematurely.
Disposing of the used or burnt-out bulbs is an environmental hazard so study the disposal instructions printed on the bulb package and follow your local code on how to get rid of CFL.