Tobacco contains over 4000 chemicals, including 63 known carcinogens. Smoking is highly addictive due to nicotine and kills more people worldwide than AIDS, automobile accidents, alcohol, fires, homicides, suicides, and drug overdoses combined. Starting at a young age puts one at high risk of lifelong addiction and negative health consequences, including various cancers and premature death. Secondhand smoke also endangers others, especially infants and children. Quitting smoking has significant health benefits.