Tobacco is an agricultural prouct processed from the fresh leaves of plants in the genus Nicotiana. It is most commonly smoked in the form of cigarettes or cigars. Tobacco has been growing on both American continents since about 6000 BC and was used by native cultures by around 3000 BC. It has been smoked, in one form or another, since about 3000 BC. Tobacco has a long history of use in Native American culture, and played an important role in the political, economic, and cultural history of the United States of America.