Incandescent bulbs are an inexpensive way to light the home, yet they produce 90% heat and 10% light - producing heat consumes most of the energy used by the bulb.  Compact fluorescent bulbs use a 1/4 of the power because they do not produce as much heat. 

For example, the average home typically uses 75 Watt bulbs for most light fixtures because the quality of light produced is good for most activities. Compact fluorescents are now available in both warm and cool colors, producing the same quality light using only 15 Watts per bulb.    Generally compact fluorescents are more expensive than incandescent bulbs, but they typically last 2-3 times longer, making them a worthy investment in terms of the money saved on your electric bill.

There are two types of compact fluorescent bulbs recommended for residential use, bulbs with a separate electronic ballast and those with an integrated electronic ballast.   The separate electronic ballast and bulb setup is more expensive, although it gives you the option to replace the bulb when its life is through rather than throwing it away and purchasing a new bulb and ballast.   The ballast can often be used with 2-3 different bulbs over its lifetime. 

The integrated ballast setup is usually much less expensive because you do not have purchase the bulb and ballast separately.  Yet when the bulb burns out both the bulb and ballast have to be disposed of properly.