An electronic cigarette is a rechargeable battery powered personal vaporiser (PV) or inhaler, often in the form of a cigarette, and can contain either flavoured nicotine liquid or refills with no nicotine. The nicotine strength can also be varied according to the user’s requirement. The refill is usually called e-liquid. High-power models are also available that do not resemble an ordinary cigarette but instead look like a thick tube or a small box with a mouthpiece attached.
E-cigarettes are a modern way to obtain nicotine and replace smoking – an alternative to smoking tobacco cigarettes, desirable since they are likely to be several orders of magnitude less harmful. They can also be used without nicotine. The refill liquids contain about half a dozen ingredients that are all licensed for human consumption and considered acceptably safe, as against the 5,300 discovered so far in cigarette smoke of which many are known to be toxic and/or carcinogenic.