The devices come in an array of colors, some bejeweled, others a conservative silver metal. Some light up, and others just cover the basics of heating a nicotine-laced liquid into a vapor.
Electronic cigarette stores are popping up around the country, allowing consumers to customize their reusable device. Store owners cater to these preferences, adding new flavors like cactus kooler and watermelon gum and blueberry muffin into their already wide array of samplings.
But questions swirl around e-cigarettes. And the first is, how do they work?
E-cigarettes are marketed as smoke-free devices. And while a user exhales a cloud that may look like smoke, it's actually vapor. That's because e-cigarettes are battery-powered devices containing a liquid with varying degrees of nicotine and flavoring. A user inhales, and an atomizer heats the liquid, transforming it into a vapor.
And that's why using an e-cigarette is colloquially referred to as "vaping."
When did these devices first hit the marketplace?
Electronic cigarettes first began gaining popularity in China about a decade ago and were introduced in Europe and the United States several years later, according to the Consumer Advocates for Smoke-free Alternatives Association.
The devices are sometimes touted as smoking cessation aids. Yet, this hasn't been scientifically proven since their emergence in gas stations and convenience stores, smoke shops and vaping stores, according to smokefree.gov, a website created by the Tobacco Control Research branch of the National Cancer Institute.
In 2008, the World Health Organization stated it didn't consider the devices to be a legitimate therapy for smokers trying to quit. Last year, WHO reinforced that message, stating consumers should be "strongly advised" not to use electronic cigarettes.
Public health officials echo this warning as cities like New York and Los Angeles clamor to add these battery-powered devices to existing smoking bans, according to media reports.
Yet, business is booming, as analysts estimated the e-cigarette industry reached $1.5 billion last year. Maryland and Carroll have their share of vaping stores.
So, business is prospering, but scientific evidence is inconclusive. What is the federal government saying on the matter?
Not much -- yet.
The U.S. Food and Drug Administration announced its intent to issue a proposed rule to regulate additional tobacco products. A December 2010 U.S. Court of Appeals for the D.C. Circuit decision held that e-cigarettes can be regulated as "tobacco products" under the Tobacco Control Act.
The agency cannot comment on the proposal's tentative release date, but FDA spokeswoman Jenny Haliski noted that the proposed rule has been sent to a division within the Office of Management and Budget.
Currently, the FDA has not approved any e-cigarettes for therapeutic purposes, and additional research is needed to peg down the device's harms and benefits, according to Haliski.
Who's using these devices?
About one in five American adult smokers have tried e-cigarettes as of 2011, which is double the amount who had used the devices the year before, a U.S. Centers for Disease Control and Prevention report released in February 2013 states.
Overall, about 6 percent of all adults have tried the product as of 2011, an estimate that also nearly doubled from 2010.
"E-cigarette use is growing rapidly," CDC Director Tom Frieden stated in a news release. "There is still a lot we don't know about these products, including whether they will decrease or increase use of traditional cigarettes."
Usage among high school students is also on the rise. The percentage of students who had tried an e-cigarette doubled from 4.7 percent in 2011 to 10 percent in 2012, according to a CDC report released in September. About 1.78 million middle and high school students nationwide have tried e-cigarettes.
More than 76 percent of middle and high school students who used e-cigarettes within a 30-day time frame reported that they also smoked conventional cigarettes during that same period, the September report states.
"The increased use of e-cigarettes by teens is deeply troubling," Frieden stated in a news release. "Nicotine is a highly addictive drug. Many teens who start with e-cigarettes may be condemned to struggling with a lifelong addiction to nicotine and conventional cigarettes."