A CFL is a fluorescent light bulb that has been compressed into the size of a standard-issue incandescent light bulb. Modern CFLs typically last at least six times as long and use at most a quarter of the power of an equivalent incandescent bulb.

According to Arthur Rosenfeld, a physicist and member of the California Energy Commission, “If every home in the United States replaced just one incandescent light bulb with a compact fluorescent light bulb (CFL), the energy saved would prevent greenhouse-gas emissions equivalent to taking more than 1 million cars off the road.”