An electronic cigarette, or e-cigarette, runs on a battery, either disposable or rechargeable. The airflow sensor senses when you suck in air from the mouthpiece. The sensor tells the microprocessor to turn on the heating element and start the process that turns the nicotine solution into a vapor that you inhale. Many e-cigarettes have an LED (tiny light) at the end that glows red when you inhale.

For some smokers, e-cigarettes may satisfy nicotine cravings. But the nicotine in e-cigarettes is addictive. And they do contain small amounts of harmful chemicals.

The U.S. Food and Drug Administration (FDA) has rules for e-cigarettes, including required health warnings, no sales to those younger than 18, and no free samples.

An e-cigarette cartridge contains a high concentration of nicotine that, if ingested, can be very poisonous or even fatal. Keep these cartridges out of the reach of children.