Tobaccois a product prepared from the leaves of the tobacco plant bycuringthem. The plant is categorized within the genusNicotianaof theSolanaceae(nightshade) family. While there aremore than 70 speciesof tobacco, the chief commercial crop isN. tabacum. The more potent speciesN. rusticais also widely used around the world.Tobacco contains thealkaloidnicotine, astimulant. Dried tobacco leaves are mainlysmokedincigarettes,cigars,pipe tobaccoand flavoredshisha tobacco. They are also consumed assnuff,chewing tobaccoanddipping tobacco.Tobacco use is a risk factor for many diseases, especially those affecting theheart,liverandlungs, andseveral cancers. In 2008, theWorld Health Organization(WHO) named tobacco as the world's single greatest cause of preventable death.Prevalence of tobacco useIn 2012, 21% of the global population aged 15 and above smoked tobacco. Men smoked at five times the rate of women; the average rates were 36% and 7% respectively. Smoking among men was highest in the WHO Western Pacific Region, with 48% of men smoking some form of tobacco. Smoking among women was highest in the WHO European Region at 19%.The rates at which adolescent girls aged 1315 use tobacco average around 8% globally. This average does not include the WHO European Region or the WHO African Region due to unavailability of comparable data. Among the other regions, the highest prevalences among girls are seen in the WHO Region of the Americas, where an average of almost 14% of young adolescent girls are already tobacco users. This reflects aggressive tobacco industry marketing to girls in countries with minimal laws against tobacco advertising, promotion and sponsorship. Boys aged 1315 in WHO South-East Asia Region and WHO Eastern Mediterranean Region use tobacco at higher rates than their counterparts in other regions, at over 20% in both regions.