As global tobacco use patterns evolve, smoking, vaping & harm-reduction science is gaining importance in public health and pulmonology. Traditional smoking cessation programs now coexist with research into electronic nicotine delivery systems (ENDS), heated tobacco products, and nicotine replacement therapies. While vaping is promoted by some as a harm-reduction tool, its long-term respiratory effects remain under investigation. Smoking, vaping & harm-reduction science highlights the need for balanced messaging, particularly for youth and high-risk populations. Epidemiologic studies and toxicologic analyses are essential in defining risk thresholds and shaping regulatory policies. Health education, tobacco taxation, and product labelling reforms play complementary roles in prevention efforts. A nuanced, evidence-based approach is vital to reducing global lung disease burden without inadvertently creating new dependencies.