Prevalence of daily<unk>  in 2012 The share adults who smoke any tobacco product on a daily or non-daily basis in 2016.<unk> , primarily of tobacco, is an activity that is practiced by some 1.1 billion people, and up to 1/3 of the adult population. The image of the smoker can vary considerably, but is very often associated, especially in fiction, with individuality and aloofness. Even so,<unk>  of both tobacco and cannabis can be a social activity which serves as a reinforcement of social structures and is part of the cultural rituals of many and diverse social and ethnic groups. Many smokers begin<unk>  in social settings and the offering and sharing of a cigarette is often an important rite of initiation or simply a good excuse to start a conversation with strangers in many settings; in bars, night clubs, at work or on the street. Lighting a cigarette is often seen as an effective way of avoiding the appearance of idleness or mere loitering. For adolescents, it can function as a first step out of childhood or as an act of rebellion against the adult world. Also,<unk>  can be seen as a sort of camaraderie. It has been shown that even opening a packet of cigarettes, or offering a cigarette to other people, can increase the level of dopamine (the "happy feeling") in the brain, and it is doubtless that people who smoke form relationships with fellow smokers, in a way that only proliferates the habit, particularly in countries where<unk>  inside public places has been made illegal. Other than recreational drug use, it can be used to construct identity and a development of self-image by associating it with personal experiences connected with<unk> . The rise of the modern anti-smoking movement in the late 19th century did more than create awareness of the hazards of<unk> ; it provoked reactions of smokers against what was, and often still is, perceived as an assault on personal freedom and has created an identity among smokers as rebels or outcasts, apart from non-smokers: The importance of tobacco to soldiers was early on recognized as something that could not be ignored by commanders. By the 17th century allowances of tobacco were a standard part of the naval rations of many nations and by World War I cigarette manufacturers and governments collaborated in securing tobacco and cigarette allowances to soldiers in the field. It was asserted that regular use of tobacco while under duress would not only calm the soldiers but allow them to withstand greater hardship. Until the mid-20th century, the majority of the adult population in many Western nations were smokers and the claims of anti-smoking activists were met with much skepticism, if not outright contempt. Today the movement has considerably more weight and evidence of its claims, but a considerable proportion of the population remains steadfast smokers.
Smoking
Sedentary lifestyle
Obesity
Passive smoking
Family history 
Vegetarianism
Psychiatric history
Body mass index