The e-cigarette is spreading like wildfire in Europe and the United States but has yet to make inroads in other markets.
Five percent of Europeans have tried the electronic cigarette once or twice, and two percent either use it occasionally or regularly, according to a Eurobarometer poll last year of 26,751 people in the then 27-nation European Union.
Smokers in Denmark, Greece, Romania and Poland were the most enthusiastic converts.
French tobacco addiction specialist Bertrand Dautzenberg says about 23 million Europeans tried the device in 2012, but "this figure probably doubled in 2013".
Use of the e-cig is governed in fragmented fashion by EU states. Belgium, Luxembourg, Malta and Slovenia prohibit its use in public places where smoking is also not allowed, Italy and France prohibit its sale to minors and Lithuania bans its sale as a product that imitates tobacco.
In Russia, where almost a third of the population smoke cigarettes, the electronic version has not proved a hit. Moscow adopted a law this year to ban tobacco and e-cigarette smoking in public places.
E-cig sales in the United States multiplied nine-fold from 2010 to 2012, while the number of people who tried them at least once quadrupled from 2009 to 2010, studies have shown.
The US Centers for Disease Control and Prevention (CDC) said the gadget's use had doubled among teenagers from 2011 to 2012, when the number reached 1.78 million.
Turnover, says financial services company Wells Fargo, will reach between $1 and $1.7 billion (700 million and 1.3 billion euros) by the end of this year. By comparison, the turnover of the tobacco industry is about $80 billion per year.
Regulation differs between US states, but its sale to minors is mostly prohibited.
"Vaping", or inhaling the vapour produced by the battery-powered device, is prohibited on all US planes and trains.
The cigarette has not really caught on in other continents, especially in markets where conventional cigarettes are cheap or anti-tobacco laws are relatively muted.
Prohibitions are in place in Argentina, Australia, Brazil, Colombia, Mexico, Panama, Singapore, Thailand, Uruguay and Venezuela.