E-cigarettes: Short for electronic cigarettes, e-cigarettes are electronic devices designed to mimic the experience of smoking tobacco. Also called vapes, e-cigs, vape pens, e-hookahs, and electronic nicotine delivery systems (ENDS), most e-cigarettes have a battery, a heating element, and a place to hold a liquid that usually contains nicotine. Some users also use e-cigarettes for marijuana and other drugs. Inside the e-cigarette the liquid is heated, producing an aerosol that users inhale. Using an e-cigarette is also called vaping.