Approximately 13 years ago, electronic cigarettes (ECs), also referred to as electronic nicotine delivery systems, alternative nicotine delivery systems, e-hookahs, mods, vape pens, vaporizers, vapes, and tank systems, were introduced to the US market. ECs are lithium-ion batteryoperated devices that heat a liquid, usually containing nicotine and dozens of other toxins, into an aerosol of tiny particles (sometimes called a "vapor," although this is a misnomer) that is then inhaled. ECs rapidly gained popularity among teenagers and young adults due to marketing campaigns that touted them as a safer alternative to traditional cigarettes and as a tool for reaching the goal of smoking cessation. Because of their relatively recent introduction into the US market, the long-term health effects of ECs have not been well documented.