The Great American Smokeout is a challenge to quit using tobacco Thursday. It's intended to encourage people to quit forever.

Beginnings: The Great American Smokeout began in the 1970s, when smoking was commonplace. What are the origins of the Smokeout?

Progress: In 1965, 42% of U.S. adults smoked cigarettes. That percentage has changed quite a bit.

Overseas: Despite most European countries' higher cigarette taxes and stricter smoking regulations, Europe's smoking population is larger than the U.S. smoking population. How do experts explain this disparity?

Bad influences: Some filmmakers have accepted large sums of money to place tobacco products in their characters' hands.

Uncertain censorship: Which country's high court overturned a ban on smoking in film and television?

Lowering the influence: Tobacco advertising has been greatly curbed worldwide.

Some alternatives: Are light cigarettes healthier? What about natural cigarettes?

Do it: The American Cancer Society -- the promoters of the Great American Smokeout -- provide many resources to help you quit.

Healthy trend: What do most people say is the most effective way to quit?

Why quit? Do it for your health, the money, the environment, or for the people around you.