A compact fluorescent lamp (CFL), also known as a compact p 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.
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 perceived 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.