The term ‘body temperature' normally relates to the temperature deep inside the body. This temperature must be maintained to ensure the stable operation of vital functions, including the brain, internal organs and main arteries.

Touching different parts of the body tells you that some parts feel warm and others cool. Also, measurements taken at these sites can be affected by saliva, moisture and sweat from the skin. Eating, bathing, exercising - even crying - can all affect temperature.

‘Normal temperature' is usually around 37 °C (98,6 °F). However, normal temperature is not the same for every individual. Temperature can vary with age, and even time of day. Usually it is lowest in the morning, highest in the afternoon and somewhat lower at bedtime.

To correctly tell whether someone in your family has a fever or not, it is important to know what their normal temperature is when they are well.

Fever is one of the body's defence mechanisms. When bacteria or viruses get into your body and cause it to malfunction, the body goes on the defensive and your immune system is activated. When this happens, a central nerve in the brain allows the heat generated inside the body to be turned up from the usually constant level. This higher temperature level increases the metabolism and prevents the increase of pathogenic agents.