A fever is a response to disease or infection resulting in rise in core body temperature beyond the normal 98.6 degrees F, and is characterized by warmer than usual skin temperature. Fevers are typically caused by:  

• Disease
• Infection
• Heat illness
• Sunburn
• Trauma

Heatstroke is a condition caused by exposure to natural or artificial excessive heat. Signs and signs and symptoms of heatstroke include:

• Headache
• Vertigo
• Confusion
• Hot, dry skin
• Generally slight rise in body temperature
• Severe cases-very high fever, vascular collapse, and coma

Hyperthermia is increased body temperature and metabolic rate from a fever or heavy exercise. Hypothermia is a coolness of the body and drop in body temperature from possible extended exposure to cold.