Tobacco smoking is the inhalation of smoke from burne dried or cured leaves of the tobacco plant, most often in the form of a cigarette. People may smoke casually for pleasure, habitually to satisfy an addiction to the nicotine present in tobacco and to the act of smoking, or in response to social pressure. In some societies, people smoke for ritualistic purposes. According to the WHO about one-third of the world's male population smokes tobacco, with two-thirds of all the world's smokers residing in 10 countries. In order they are China, India, Indonesia, Russia, the U.S., Japan, Brazil, Bangladesh, Germany and Turkey respectively.