Smoking has long been a habit that has never really been broken. In the old ages, smoking had been performed as a ritual, and as protection from the cold. There were no electronic cigarettes then, but people actually used herbal leaves when they smoked, but those were not the addictive kind. When tobacco was discovered as a prime leaf for smoking, it was given much more thought and attention, as the need to smoke became high as years progressed. It was then found out that the alkaloid nicotine is the most characteristic constituent of tobacco which researchers point as responsible for tobacco's addictive nature. Over the years, as more and more research are done, harmful effects of tobacco were found to derive from the thousands of different compounds generated in the smoke, including polycyclic aromatic hydrocarbons, formaldehyde, cadmium, nickel, arsenic, radioactive polonium-210, tobacco-specific nitrosamines (TSNAs), phenols, and many others.
I guess with this harmful nature and the harm that it can do to the body, people are now are contemplating on quitting the habit. With the invention of the electronic cigarette, smoking can now be regulated, and nicotine levels are now being controlled while one smokes.