A compact fluorescent lamp (CFL), also known as a compact fluorescent light or energy saving light (or less commonly as a compact fluorescent tube [CFT]), is a type of
fluorescent lamp. Many CFLs are designed to replace an
incandescent lamp and can fit into most existing
light fixtures formerly used for incandescents.
Compared to general service incandescent lamps giving the same
amount of visible light, CFLs use less power and have a longer rated life. In the United States, a CFL has a higher purchase price than an incandescent lamp, but can save over 30
US$ in electricity costs over the lamp's life time.
[2] Like all fluorescent lamps, CFLs contain
mercury, which complicates their disposal.
CFLs radiate a different light spectrum from that of incandescent lamps. Improved
phosphor formulations have improved the subjective color of the light emitted by CFLs such that some sources rate the best 'soft white' CFLs as subjectively similar in color to standard incandescent lamps.
[3]