Body Temperature is a measure of the body's ability to generate and get rid of heat. The body is very good at keeping its temperature within a narrow, safe range in spite of large variations in temperatures outside of the body.
The average normal temperature is 98.6°F (37°C). But "normal" varies from person to person. Your temperature will also change throughout the day (as much as 1°F (0.6°C) or more above or below 98.6° depending on how active you are and the time of day.
An abnormally low body temperature (hypothermia) can be serious, even life-threatening. Low body temperature may occur from cold exposure, shock, etc. A low body temperature may also be present with infection.
A high body temperature can be just as dangerous. Heatstroke occurs when the body fails to regulate its own temperature, and body temperature continues to rise. Heatstroke causes severe dehydration and can cause body organs to stop functioning.