While heroic bystanders have given first aid that saved someone's life, only half of U.S. residents over age 18 are trained to perform CPR or stop serious bleeding, a new study finds.
If the first number that pops into your head when you think about body temperature is 98.6°F, you have a study from 1851 to thank for that. Carl Reinhold August Wunderlich, a German doctor, took multiple axillary (armpit) temperatures from about 25,000 people, and based on an analysis, he established 98.6°F (or 37°Celsius) as the norm.
The reality though is that normal body temperature is on a spectrum, not an absolute. Body temperature can depend on your age, the time of day, and what you were doing before you popped the thermometer in your mouth or zapped your forehead.
If you’re wondering whether your numbers are normal (and what to do if they’re not), or even if you’re using the thermometer the right way, consider this your crash course on everything body temperature-related.