Smoking refers to the inhalation of smoke from various sources like cigarettes, cigars, beedis, pipes or hookahs. The nicotine in tobacco is very addictive and it kills more people than all other recreational drugs put together. The habit is linked to a variety of diseases, including cancer. In fact one out of three cancer cases is caused due to tobacco use. It is the biggest avoidable cause of death in the world and along with alcohol, junk food and a sedentary lifestyle, the main cause for the rise in lifestyle diseases like diabetes, hypertension and cardiovascular ailments.