What is core body temperature?

The widely accepted average of normal, or core, body temperatures is 98.6 degrees Fahrenheit, according to Web MD. This benchmark temperature was developed in the 19th century by Carl Wunderlich, a German physician who averaged over a million temperatures from the armpits of 25,000 people, according to Harvard Health.

Web MD states that body temperature may be measured from multiple places on the body, including the ear, mouth, armpit and rectum. "Normal" body temperature can vary by up to 1 degree above or below 98.6 degrees Fahrenheit, and is affected by physical activity, hormone levels and ovulation. Anything over 100 degrees Fahrenheit indicates a fever, which most often means the body is fighting an infection.