An electronic cigarette (or e-cigarette), electronic vaping device, personal vaporizer (PV), or electronic nicotine delivery system (ENDS) is a battery-powered device which simulates tobacco smoking. It generally uses a heating element that vaporizes a liquid solution. Some solutions contain a mixture of nicotine and flavourings, while others release a flavoured vapor without nicotine. Many are designed to simulate smoking implements, such as cigarettes or cigars, in their use and/or appearance, while others are considerably different in appearance.
Electronic cigarettes were invented in China in 2004 and have made their way across the world to the USA and other countries rather recently. While they are not recognized by the FDA as a stop smoking aid, most people you will talk to who use them did in fact use them to stop smoking regular cigarettes. You will have to make up your own mind on whether or not you think they are a healthier alternative to smoking, but numerous (non-governmental) studies show that they are up to 1,000 times less deadly and are in fact about as harmful as wearing a patch or chewing the gum.