In the last few years, there has been a proliferation of compact fluorescent light bulbs in the market. You can get a compact fluorescent light bulb in an enormous array of shapes, sizes, wattages, colors and for many different applications. A CFL Light Bulb can come in a standard base which is the most common size. A standard base CFL bulb has a screw in base and is typically used in light fixtures and lamps. In a standard or medium base (E26), you can get compact fluorescent light bulbs of a wide range of wattages from a 5W (15-25W incandescent equivalent) to over 25W (75w-100W incandescent equivalent). The CFL bulbs can come in different shapes such as spirals, torpedos and candles for decorative use such chandeliers and sconces, capsules or A lamps typically used in lamps and globes which are commonly found in open bathroom vanity fixtures. CFL bulbs have also evolved to provide dimmable functions and can work with most dimming switches. Three-way CFL Bulbs are now available that will produce three levels of light when used in a lamp socket with a three-way switch.
CFL bulbs are come in wide spectrum of colors ranging from a warm color (2700 Kelvin color temperature) to Daylight CFL bulbs that have a color temperature of at least 5000 degrees Kelvin, which produces a very white daylight-like light. Also available are Colored CFL Bulbs, commonly found in yellow and pink color. Soft pink colored bulbs can be found in restaurants and restrooms as they product a soft pleasant color and therefore enhance the look of objects in a room. A bulb producing yellow light is difficult for many flying insects to see and therefore is appropriate for use where people gather.
One of the most common type standard bulbs around, reflector bulbs are used in recessed lights which are enormously popular in homes and commercial application such as hotels, restaurants and apartment buildings. Reflectors or R-lamps are predominantly the incandescent type and found in the 40-100 watt range. CFL Reflectors draw a fraction of the power of the incandescent equivalents and therefore can save enormous amounts of energy. CFL Reflector bulbs come in various sizes to suit specific needs. Dimmable CFL Reflectors, wet location, outdoor, cold weather and dark sky variations are now available.
CFL Candelabra base bulbs also have a screw in base but have a smaller footprint than a standard base. They are typically used in decorative wall sconces, some ceiling fan fixtures, and chandeliers. Another type of a base for Compact Fluorescent Light is the GU24. CFL GU24 light bulbs have two spikes projecting from the base instead of the usual screw in base. These spikes insert into corresponding holes in the fixture's socket and you twist the bulb to lock it into place. GU24 bulbs don’t require a separate ballast in that they are self-ballasted. However, you can easily replace the ballast portion of a GU24 bulb.
GU10 base compact fluorescent bulbs have a similar configuration to the Gu24 in that they have the two protruding pikes that insert into corresponding holes in the socket. GU10 base bulbs are typically halogen reflector lamps.
A Mogul base Compact fluorescent Light bulb (E39) has a screw in base but is different in size than a standard medium size (E26) base. Mogul base bulbs work in specific light fixtures and the bulbs tend to be higher in wattage.
Pin Base Compact Fluorescent Light bulbs as their name suggests, have pins for a base which plug into a socket, as opposed to screwing into a socket with screw in base bulbs. Compact Pin Based Fluorescent Lights are much smaller than the Fluorescent Tube bulb variety. Pin Base bulbs typically come in bi pin or 4 pin configurations. They come in various shapes e.g. quads, spirals, triples and twins. Pin Base light bulbs require ballast for operation. The main difference between screw in CFL bulbs and Pin base CFL bulbs is that the latter is designed more for dedicated fixtures.
Source: Conservation Mart (http://www.conservationmart.com)