The key components of an electronic cigarette include a rechargeable battery, a heating element or atomizer, and a cartridge or tank to hold the e-liquid. When a user inhales through the device's mouthpiece, the battery powers the heating element, which then heats up the e-liquid to create a vapor. This vapor is rich in flavor and may contain nicotine, although nicotine-free options are also available, catering to both smokers and non-smokers.