Nicotine is a naturally occurring, addictive chemical found in the leaves of the tobacco plant. Although tobacco was unknown to Europe before Columbus's historic journey, it grew naturally in the Americas and was used by many native tribes. In the five centuries after Columbus brought tobacco back to Europe, tobacco use spread to every known culture.

Governments have reacted in many different ways to the proliferation of tobacco in their countries—from taxation, penalties, or even death to encouraging tobacco's production so that the government could profit from it. With automation and advertising, tobacco use grew exponentially throughout the first half of the twentieth century. Almost 50 million Americans inhale or ingest tobacco in the form of cigarettes, smokeless tobacco, or other tobacco products. It is one of the few legal drugs available today, and its popularity...