Whether you are purchasing a light, changing a switch, or replacing a burned out bulb, you need to coordinate each of those three components of the system. When you are at the hardware store or the lighting store to buy a lighting product you are confronted with the myriad of fixture, switch and lamp options. I am going to try and help you choose the pieces you need to be successful.
When buying a bub or a fixture or planning the lighting of a new space consider these three parts of the lighting circuit together: the bulb, the light fixture and the switch.
The Bulb. The part that is going to produce the light is the best place to start when choosing how you will light a space. For residential lighting there are two primary categories of bulb or lamp: bulbs that employ transformers, and bulbs that don't. Bulbs that use transformers include fluorescent lights (the rectangular ones with the light sabers) compact florescent light bulbs (CFL) and LED bulbs. The bulbs that don't are incandescent bulbs including halogen lights. Within these sub categories there are other divisions that produce light of different qualities and have different longevity, power consumption and aesthetics making the topic broad enough to warrant another blog post. For all of the variation in styles and type the most important aspect is whether or not there is a transformer involved in making light.
The Fixture. Most fixtures for residential lighting receive the same standard bulb base (the part that screws into the fixture), although there are exceptions. A fixture that excepts bulbs with a standard screw in base is more versatile than fixtures that don't. An 'Energy Star' fixture has a different style receptacle to prevent inefficient bulbs from being used in it. If you have selected a halogen bulb it will not be compatible with an 'Energy Star' fixture. There are also some fixtures that require push in style bulbs or other variations of bulb bases that are not universal between bulb type. Most of the time though you can find your preferred bulb in style of base that will be compatible with the fixture that fits your vision even if that means ordering it online and waiting a couple of weeks for a bulb.
The Switch. Standard on/off switches are universally compatible with bulbs that use transformers and bulbs that don't, but switches that dim the lights are not universally compatible. Dimming switches are available for both of the two broad categories of bulb that I have laid out. On the switch there will be some writing that indicates whether it is designed for incandescent bulbs or LED and fluorescent bulbs. If you use the wrong switch the lights won't dim properly and the switch may overheat and fail.
There are some lights that don't fit into the generalizations above. These are architectural lights- the rectangular florescent lights that we have in our offices and work shops that use separate bulbs and ballasts. Although we almost exclusively see these controlled by the standard on/off switch, these lights are dimmable too. For architectural lights you need to have a dimming switch that is compatible with the specific ballast in the fixture. The manufacturer of the ballast will be able to tell you the model numbers of the switch that you would need to use.
I hope that this rather dense blog post gives you a little information to make it easier next time you need to upgrade some light bulbs or replace a light fixture in your house. Email me if you have some questions, or of course if you need an electrician.