An electronic cigarette (e-cig  e-cigarette vaporizer e-shisha shisha pen)

 is a battery-powered vaporizer which simulates smoking by producing a flavoured vapour with or without nicotine that resembles smoke. It generally uses a heating element known as an atomizer, that vaporizes a liquid solution known as e-liquid. 

E-liquids usually contain a mixture of propylene glycol,vegetable glycerine, nicotine(optional) and flavorings 

The benefits and risks of electronic cigarette use are uncertain. Some evidence suggests e-cigarettes may be safer than smoking tobacco products, and possibly as safe as other nicotine replacement products