Electronic cigarettes should be held between the index finger and thumb, the same way one holds the hand of a mouse when going for a walk. Practice the proper grip with this Groupon.

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• $11 for $20 worth of e-cigarettes and accessories

Electronic Cigarettes: No Smoke, No Fire

Nearly five million electronic cigarettes were sold in the United States in 2012—a sign of their ever-increasing popularity. Read on to learn more about this smoke-less phenomenon.

E-cigarette: A device that uses battery power to heat a liquid mixture for users to inhale as a vaporized aerosol. Also known as an e-cig, electronic vaping device, personal vaporizer, or electronic nicotine delivery system (ENDS), an e-cigarette may resemble a real cigarette or look much different, depending on the model and added attachments (“mods”).

Vaping: The act of inhaling vaporized liquid from an e-cigarette. Users often call themselves “vapers”—not to be confused with the all-ghost barbershop quartet known as The Vapors.

E-liquid: The stuff, also known as "juice," that gets vaporized inside the e-cig. The solution usually consists of water and either vegetable glycerin or propylene glycol—the same substance (recognized by the FDA as safe for use as a food additive) that smoke machines use to create fake smoke. Juices come in a variety of flavors, including fruit, coffee, and tobacco.

Milligrams: The unit by which e-liquids typically measure the amount of nicotine in the formula. Concentrations can be as high as 24 milligrams to as low as none at all—an ideal option for users who simply want the sensation of vaping without the addictive element.

Atomizer: The heating element that vaporizes the e-liquid. When the atomizer is permanently attached to the e-liquid cartridge, it’s called a cartomizer. Atomizers are durable and meant to be paired with refillable juice cartridges, while cartomizers are generally found on models designed for short-term use.