A, B, C, and D. Learn what each of these Medicare parts covers, including hospital, medical, and prescription drug coverage.

In the penultimate episode of Crash Course Zoology, we use everything we've learned so far to try and figure out what a "species" even is anyway! As you'll see, the incredible diversity of animals ...

I love simple questions that wind up having complicated—or at least not straightforward—answers. Astronomers twist themselves into knots, for example, trying to define what a planet is, even though it ...

Haupt is a health and wellness editor at TIME. Photo-Illustration by Chloe Dowling for TIME (Source Images: urbancow/Getty Images, ozgurdonmaz/Getty Images, Sparrow and Snow/sparrowandsnow via ...