It's been a little over a decade since the modern e-cigarette hit markets across the globe. Since its arrival, it's inspired waves of controversy from doctors and public health officials, particularly in the United States. E-cigarettes dispense a liquid cocktail of nicotine mixed with tasty flavors, which is vaporized and inhaled. Because they deliver nicotine without also delivering the harmful, cancer-causing chemicals that traditional combustible cigarettes provide, many groups have hailed them to be a safer alternative to smoking. But not all agree. In May of last year, the FDA banned the sale of e-cigarettes to anyone younger than 18, regulating the devices in much the same way as their traditional counterparts. The CDC's reasoning is that they are a gateway for children and teens to go on to use combustible cigarettes, and that the levels of nicotine in them aren't considered safe for them.