It was the first day of spring break in 1992 in Phoenix, and 12-year-old Heather Smith was excited for her family's upcoming ski trip. But before Smith and her family had even packed their snow pants, ...

A tiny organ plays a larger role in maintaining health than previously thought. The appendix is often dismissed as an unnecessary organ. But Brigham and Women’s Hospital researchers found it plays a ...

Visit NAP.edu/10766 to get more information about this book, to buy it in print, or to download it as a free PDF.

Your immune system is your body’s built-in defense network, working nonstop to protect you from bacteria, viruses, and other harmful invaders. Your immune system includes two main parts: the innate ...