Electronic cigarettes are battery-powered devices that heat a liquid to produce an aerosol for inhalation. Many have a battery, heating element, mouthpiece, and a cartridge or tank that holds the liquid; designs differ in shape and in whether the liquid supply is replaceable or refillable. This collection centers on e-cigarette devices, with examples that include a cigar-style form as well as related refilling and charging items. The word "vapor" is often used for the aerosol, though it is not simply water vapor. Liquid ingredients vary, and some e-cigarette liquids contain nicotine.