Commonly referred to as CFLs, compact fluorescent light bulbs are rapidly replacing traditional incandescent light bulbs for residential use. However, controversy and even comic parody have arisen surrounding CFL use. CFLs contain small amounts of mercury, and several public forums and news agencies have been announcing that the breakage of a CFL in one's home may result in exposure to dangerously high mercury levels that can cause serious physical side effects. The purpose of this article is to introduce the basics of how incandescent and compact fluorescent light bulbs work, explain why the switch to CFLs is being promoted, and summarize the potential hazards of CFL use for the residential consumer. (Contains 2 figures.)