Smoking is responsible for 5 million deaths worldwide each year, with half of all long-term smokers eventually dying from tobacco use. Tobacco use is influenced by neurochemical, environmental, and individual factors. Nicotine acts on the brain's reward system and cues in the environment like peer pressure and advertising can influence tobacco use. Genetics also play a role, as psychiatric disorders are associated with higher rates of tobacco dependence. Treatment involves both pharmacotherapy like nicotine replacement therapy and non-pharmacologic interventions like counseling, with the combination of treatments being most effective at helping smokers quit.