E-cigarettes, or electronic cigarettes, are battery-operated smoking devices. They often look like cigarettes, but work differently. Using an e-cigarette is called vaping. The user puffs on the mouthpiece of a cartridge. This causes a vaporizer to heat the liquid inside the cartridge. The liquid contains nicotine, flavorings, and other chemicals. The heated liquid turns into the vapor that is inhaled.
Some people think that e-cigarettes are safer than cigarettes, and that they can be used to help people quit smoking. But not much is known about the health risks of using them, or whether they do help people quit smoking. However we do know about some dangers of e-cigarettes:
NIH: National Institute on Drug Abuse