Nicotine is a highly addictive substance found in tobacco products and e-liquids for electronic cigarettes. It can be naturally extracted from tobacco plants or synthesized in labs, and is also used as a pesticide. Tobacco products, including cigarettes, cigars, heated tobacco, and most e-cigarettes, contain nicotine. This article covers the history and impact of nicotine, its health effects, and treatment options for nicotine dependence