People have used tobacco for centuries, cigarettes did not appear in mass-manufactured form until the 19th century. Since then, the practice of cigarette smoking has spread worldwide on a massive scale.
Today, about one in three adults, or 1.1 billion people, smoke. Of these, about 80 percent live in low- and middle-income countries. Partly because of growth in the adult population, and partly because of increased consumption, the total number of smokers is expected to reach about 1.6 billion by 2025.