They're added to breakfast cereal, bread, and even Pop-Tarts, giving the sweetest, most processed treats a halo of health. Most people pop an extra dose for good measure, perhaps washing it down with fortified milk. But what are vitamins—and how did their discovery make America's processed food...

The Klamath River on the California-Oregon border was once the third largest salmon river in the continental U.S. There were so many fish, indigenous histories claim that you could cross the river walking across their backs—which made the peoples who lived in this remote, beautiful region some of...

Today, a half century after Neil Armstrong took one small step onto the surface of the Moon, there are still just ten humans living in space—the crew of the International Space Station. But, after decades of talk, both government agencies and entrepreneurs are now drawing up more concrete plans...