They resemble the genuine thing. Completion glows as you breathe in. As you breathe out, you puff out a cloud of what looks like smoke. It s vapor, much like the fog you may see at rock shows, says M. Brad Drummond, MD. He s an assistant teacher of medicine at Johns Hopkins University School of Medication.All e-cigarettes work generally the exact same method. Inside, there s a battery, a heating element, and a cartridge that holds nicotine and other liquids and flavorings. Features and expenses differ. Some are non reusable. Others have a rechargeable battery and refillable cartridges.Using an e-cigarette is called vaping. .